=============================================================================
                                 UNITED STATES
                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C.  20549
                                 SCHEDULE 13D
                Under the Securities and Exchange Act of 1934

                             

                      Allison Transmission Holdings, Inc.
               ------------------------------------------------
                               (Name of Issuer)

                                 Common Stock
                ------------------------------------------------
                        (Title of Class of Securities)

                                 01973R101
                ------------------------------------------------
                               (CUSIP Number)

                           Allison Bennington, Esq.
                              ValueAct Capital
                       435 Pacific Avenue, Fourth Floor
                          San Francisco, CA  94133 
                               (415) 362-3700
                ------------------------------------------------
                 (Name, address and telephone number of Person
                Authorized to Receive Notices and Communications)

                           Allison Bennington, Esq.
                              ValueAct Capital
                       435 Pacific Avenue, Fourth Floor
                          San Francisco, CA  94133 
                               (415) 362-3700

                             November 11, 2013
                ------------------------------------------------
             (Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition that is the subject of this Schedule 13D, and is filing this
schedule because of 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the
following box [ ].

Note:  Schedules filed in paper format shall include a signed original and five
copies of the schedule, including all exhibits. See Rule 240.13d-7 for other
parties to whom copies are to be sent.

*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities,
and for any subsequent amendment containing information which would alter 
disclosures provided in a prior cover page.

This information required on the remainder of this cover page shall not be
deemed to be "filed" for the purpose of Section 18 of the Securities Exchange
Act of 1934 ("Act") or otherwise subject to the liabilities of that section of
the Act but shall be subject to all other provisions of the Act (however, see
the Notes).
=============================================================================


                                SCHEDULE 13D
--------------------------                          -------------------------
CUSIP NO. 00724F101                                             Page 2 of 13
-----------------------------------------------------------------------------
1. NAME OF REPORTING PERSON/S.S. OR I.R.S. INDENTIFICATION NO. OF ABOVE
   PERSON (entities only)

   ValueAct Capital Master Fund, L.P. 
-----------------------------------------------------------------------------
2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*                  (a) [X]
                                                                      (b) [ ]
-----------------------------------------------------------------------------
3. SEC USE ONLY

-----------------------------------------------------------------------------
4. SOURCE OF FUNDS (See Instructions)*  

   WC*
-----------------------------------------------------------------------------
5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
   PURSUANT TO ITEMS 2(d) or 2(e)                                         [ ]
-----------------------------------------------------------------------------
6. CITIZENSHIP OR PLACE OF ORGANIZATION 

   British Virgin Islands
-----------------------------------------------------------------------------
                    7.  SOLE VOTING POWER
                        0
   NUMBER OF       ----------------------------------------------------------
   SHARES           8.  SHARED VOTING POWER
   BENEFICIALLY         18,025,204**
   OWNED BY EACH   ----------------------------------------------------------
   PERSON WITH      9.  SOLE DISPOSITIVE POWER
                        0
                   ----------------------------------------------------------
                   10.  SHARED DISPOSITIVE POWER
                        18,025,204**
-----------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 
    18,025,204**
-----------------------------------------------------------------------------
12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
    CERTAIN SHARES                                                        [ ]
-----------------------------------------------------------------------------
13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

   9.9%
-----------------------------------------------------------------------------
14. TYPE OF REPORTING PERSON

    PN
-----------------------------------------------------------------------------
*See Item 3
**See Item 2 and 5


                                SCHEDULE 13D
--------------------------                          -------------------------
CUSIP NO. 00724F101                                             Page 3 of 13
----------------------------------------------------------------------------
1. NAME OF REPORTING PERSON/S.S. OR I.R.S. INDENTIFICATION NO. OF ABOVE
   PERSON (entities only)

   VA Partners I, LLC 
-----------------------------------------------------------------------------
2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*                  (a) [X]
                                                                      (b) [ ]
-----------------------------------------------------------------------------
3. SEC USE ONLY

-----------------------------------------------------------------------------
4. SOURCE OF FUNDS*

   00*
-----------------------------------------------------------------------------
5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
   PURSUANT TO ITEMS 2(d) or 2(e)                                         [ ]
-----------------------------------------------------------------------------
6. CITIZENSHIP OR PLACE OF ORGANIZATION

   Delaware
-----------------------------------------------------------------------------
                    7.  SOLE VOTING POWER
                        0
   NUMBER OF       ----------------------------------------------------------
   SHARES           8.  SHARED VOTING POWER
   BENEFICIALLY         18,025,204**
   OWNED BY EACH   ----------------------------------------------------------
   PERSON WITH      9.  SOLE DISPOSITIVE POWER
                        0
                   ----------------------------------------------------------
                   10.  SHARED DISPOSITIVE POWER
                        18,025,204**
-----------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 
    18,025,204**
-----------------------------------------------------------------------------
12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
    CERTAIN SHARES                                                        [ ]
-----------------------------------------------------------------------------
13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

    9.9%
-----------------------------------------------------------------------------
14. TYPE OF REPORTING PERSON

    00 (LLC)
-----------------------------------------------------------------------------
*See Item 3
**See Item 2 and 5


                                SCHEDULE 13D
--------------------------                          -------------------------
CUSIP NO. 00724F101                                             Page 4 of 13
----------------------------------------------------------------------------
1. NAME OF REPORTING PERSON/S.S. OR I.R.S. INDENTIFICATION NO. OF ABOVE
   PERSON (entities only)

   ValueAct Capital Management, L.P. 
-----------------------------------------------------------------------------
2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*                  (a) [X]
                                                                      (b) [ ]
-----------------------------------------------------------------------------
3. SEC USE ONLY

-----------------------------------------------------------------------------
4. SOURCE OF FUNDS*

   00*
-----------------------------------------------------------------------------
5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
   PURSUANT TO ITEMS 2(d) or 2(e)                                         [ ]
-----------------------------------------------------------------------------
6. CITIZENSHIP OR PLACE OF ORGANIZATION

   Delaware
-----------------------------------------------------------------------------
                    7.  SOLE VOTING POWER
                        0
   NUMBER OF       ----------------------------------------------------------
   SHARES           8.  SHARED VOTING POWER
   BENEFICIALLY         18,025,204**
   OWNED BY EACH   ----------------------------------------------------------
   PERSON WITH      9.  SOLE DISPOSITIVE POWER
                        0
                   ----------------------------------------------------------
                   10.  SHARED DISPOSITIVE POWER
                        18,025,204**
-----------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 
    18,025,204**
-----------------------------------------------------------------------------
12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
    CERTAIN SHARES                                                        [ ]
-----------------------------------------------------------------------------
13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

    9.9%
-----------------------------------------------------------------------------
14. TYPE OF REPORTING PERSON

    PN
-----------------------------------------------------------------------------
*See Item 3
**See Item 2 and 5


                                SCHEDULE 13D
--------------------------                          -------------------------
CUSIP NO. 00724F101                                             Page 5 of 13
----------------------------------------------------------------------------
1. NAME OF REPORTING PERSON/S.S. OR I.R.S. INDENTIFICATION NO. OF ABOVE
   PERSON (entities only)

   ValueAct Capital Management, LLC 
-----------------------------------------------------------------------------
2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*                  (a) [X]
                                                                      (b) [ ]
-----------------------------------------------------------------------------
3. SEC USE ONLY

-----------------------------------------------------------------------------
4. SOURCE OF FUNDS*

   00*
-----------------------------------------------------------------------------
5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
   PURSUANT TO ITEMS 2(d) or 2(e)                                         [ ]
-----------------------------------------------------------------------------
6. CITIZENSHIP OR PLACE OF ORGANIZATION

   Delaware
-----------------------------------------------------------------------------
                    7.  SOLE VOTING POWER
                        0
   NUMBER OF       ----------------------------------------------------------
   SHARES           8.  SHARED VOTING POWER
   BENEFICIALLY         18,025,204**
   OWNED BY EACH   ----------------------------------------------------------
   PERSON WITH      9.  SOLE DISPOSITIVE POWER
                        0
                   ----------------------------------------------------------
                   10.  SHARED DISPOSITIVE POWER
                        18,025,204**
-----------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 
    18,025,204**
-----------------------------------------------------------------------------
12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
    CERTAIN SHARES                                                        [ ]
-----------------------------------------------------------------------------
13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

    9.9%
-----------------------------------------------------------------------------
14. TYPE OF REPORTING PERSON

    00 (LLC)
-----------------------------------------------------------------------------
*See Item 3
**See Item 2 and 5


                                SCHEDULE 13D
--------------------------                          -------------------------
CUSIP NO. 00724F101                                             Page 6 of 13
-----------------------------------------------------------------------------
1. NAME OF REPORTING PERSON/S.S. OR I.R.S. INDENTIFICATION NO. OF ABOVE
   PERSON (entities only)

   ValueAct Holdings, L.P. 
---------------------------------------------------------------------------
2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*                  (a) [X]
                                                                      (b) [ ]
-----------------------------------------------------------------------------
3. SEC USE ONLY

---------------------------------------------------------------------------
4. SOURCE OF FUNDS*

   00*
----------------------------------------------------------------------------- 
5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
   PURSUANT TO ITEMS 2(d) or 2(e)                                         [ ]
-----------------------------------------------------------------------------
6. CITIZENSHIP OR PLACE OF ORGANIZATION

   Delaware
-----------------------------------------------------------------------------
                    7.  SOLE VOTING POWER
                        0
   NUMBER OF       ----------------------------------------------------------
   SHARES           8.  SHARED VOTING POWER
   BENEFICIALLY         18,025,204**
   OWNED BY EACH   ----------------------------------------------------------
   PERSON WITH      9.  SOLE DISPOSITIVE POWER
                        0
                   ----------------------------------------------------------
                   10.  SHARED DISPOSITIVE POWER
                        18,025,204**
-----------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 
    18,025,204**
-----------------------------------------------------------------------------
12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
    CERTAIN SHARES                                                        [ ]
-----------------------------------------------------------------------------
13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

    9.9%
-----------------------------------------------------------------------------
14. TYPE OF REPORTING PERSON

    PN
-----------------------------------------------------------------------------
*See Item 3
**See Items 2 and 5


                                SCHEDULE 13D
--------------------------                          -------------------------
CUSIP NO. 00724F101                                             Page 7 of 13
-----------------------------------------------------------------------------
1. NAME OF REPORTING PERSON/S.S. OR I.R.S. INDENTIFICATION NO. OF ABOVE
   PERSON (entities only)

   ValueAct Holdings GP, LLC 
---------------------------------------------------------------------------
2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*                  (a) [X]
                                                                      (b) [ ]
-----------------------------------------------------------------------------
3. SEC USE ONLY

-----------------------------------------------------------------------------
4. SOURCE OF FUNDS*

   00*
-----------------------------------------------------------------------------
5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
   PURSUANT TO ITEMS 2(d) or 2(e)                                        [ ]
-----------------------------------------------------------------------------
6. CITIZENSHIP OR PLACE OF ORGANIZATION

   Delaware
-----------------------------------------------------------------------------
                   7.  SOLE VOTING POWER
                        0
   NUMBER OF       ----------------------------------------------------------
   SHARES          8.  SHARED VOTING POWER
   BENEFICIALLY        18,025,204**
   OWNED BY EACH   ----------------------------------------------------------
   PERSON WITH     9.  SOLE DISPOSITIVE POWER
                        0
                   ----------------------------------------------------------
                   10.  SHARED DISPOSITIVE POWER
                        18,025,204**
-----------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 
    18,025,204**
-----------------------------------------------------------------------------
12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
    CERTAIN SHARES                                                        [ ]
-----------------------------------------------------------------------------
13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

    9.9%
-----------------------------------------------------------------------------
14. TYPE OF REPORTING PERSON

    00 (LLC)
-----------------------------------------------------------------------------
*See Item 3
**See Items 2 and 5





--------------------------                          -------------------------
CUSIP NO. 00724F101                                             Page 8 of 13
-----------------------------------------------------------------------------
Item 1.     Security and Issuer

       This Schedule 13D relates to the Common Stock (the "Common Stock") of 
Allison Transmission Holdings, Inc., a Delaware corporation (the "Issuer").  
The address of the principal executive offices of the Issuer is One Allison 
Way, Indianapolis, Indiana 46222. 

Item 2.     Identity and Background 

       This statement is filed jointly by (a) ValueAct Capital Master Fund, 
L.P. ("ValueAct Master Fund"), (b) VA Partners I, LLC ("VA Partners I"), (c) 
ValueAct Capital Management, L.P. ("ValueAct Management L.P."), (d) ValueAct 
Capital Management, LLC ("ValueAct Management LLC"), (e) ValueAct Holdings, 
L.P. ("ValueAct Holdings") and (f) ValueAct Holdings GP, LLC ("ValueAct 
Holdings GP")(collectively, the "Reporting Persons").

       ValueAct Master Fund is a limited partnership organized under the laws 
of the British Virgin Islands.  It has a principal business address of 435 
Pacific Avenue, Fourth Floor, San Francisco, CA 94133. 

        VA Partners I is a Delaware limited liability company, the principal 
business of which is to serve as the General Partner to ValueAct Master Fund.  
It has a principal business address of 435 Pacific Avenue, Fourth Floor, San 
Francisco, CA 94133. 

        ValueAct Management L.P. is a Delaware limited partnership which 
renders management services to ValueAct Master Fund.  ValueAct Management LLC 
is a Delaware limited liability company, the principal business of which is 
to serve as the General Partner to ValueAct Management L.P.  Each has a 
principal business address of 435 Pacific Avenue, Fourth Floor, San 
Francisco, CA 94133.

       ValueAct Holdings is a Delaware limited partnership and is the sole 
owner of  the limited partnership interests of ValueAct Management L.P. and 
the membership interests of ValueAct Management LLC and is the majority owner 
of the membership interests of VA Partners I.  ValueAct Holdings GP is a 
Delaware limited liability company, the principal business of which is to 
serve as the General Partner to ValueAct Holdings.  Each has a principal 
business address of 435 Pacific Avenue, Fourth Floor, San Francisco, CA 
94133.

       (d) and (e). None of the entities or persons identified in this Item 2 
has during the past five years been convicted of any criminal proceeding 
(excluding traffic violations or similar misdemeanors), nor been a party to a 
civil proceeding of a judicial or administrative body of competent judgment, 
decree or final order enjoining future violations of, or prohibiting or 
mandating activities subject to, federal or state securities laws or finding 
any violation with respect to such laws.

Item 3.     Source and Amount of Funds or Other Consideration

     The source of funds used for the purchase of the Issuer's securities
was the working capital of ValueAct Master Fund. The aggregate funds used by 
these Reporting Persons to make the purchases were $311,550,000.  



--------------------------                          -------------------------
CUSIP NO. 00724F101                                             Page 9 of 13
-----------------------------------------------------------------------------

Item 4.     Purpose of Transaction

      The Reporting Persons have acquired the Issuer's Common Stock for 
investment purposes, and such purchases have been made in the Reporting 
Persons' ordinary course of business.

      In pursuing such investment purposes, the Reporting Persons may further 
purchase, hold, vote, trade, dispose or otherwise deal in the Common Stock at 
times, and in such manner, as they deem advisable to benefit from changes in 
market prices of such Common Stock, changes in the Issuer's operations, 
business strategy or prospects, or from sale or merger of the Issuer.  To 
evaluate such alternatives, the Reporting Persons will routinely monitor the 
Issuer's operations, prospects, business development, management, competitive 
and strategic matters, capital structure, and prevailing market conditions, 
as well as alternative investment opportunities, liquidity requirements of 
the Reporting Persons and other investment considerations.  Consistent with 
its investment research methods and evaluation criteria, the Reporting 
Persons may discuss such matters with management or directors of the Issuer, 
other shareholders, industry analysts, existing or potential strategic 
partners or competitors, investment and financing professionals, sources of 
credit and other investors.  Such factors and discussions may materially 
affect, and result in, the Reporting Persons' modifying their ownership of 
Common Stock, exchanging information with the Issuer pursuant to appropriate 
confidentiality or similar agreements, proposing changes in the Issuer's 
operations, governance or capitalization, or in proposing one or more of the 
other actions described in subsections (a) through (j) of Item 4 of Schedule 
13D.

      The Reporting Persons reserve the right to formulate other plans and/or 
make other proposals, and take such actions with respect to their investment 
in the Issuer, including any or all of the actions set forth in paragraphs 
(a) through (j) of Item 4 of Schedule 13D, or acquire additional Common Stock 
or dispose of all the Common Stock beneficially owned by them, in the public 
market or privately negotiated transactions.  The Reporting Persons may at 
any time reconsider and change their plans or proposals relating to the 
foregoing.

Item 5.    Interest in Securities of the Issuer

       (a) and (b).  Set forth below is the beneficial ownership of shares of 
Common Stock of the Issuer for each person named in Item 2.  Shares reported 
as beneficially owned by ValueAct Master Fund are also reported as 
beneficially owned by (i) ValueAct Management L.P. as the manager of each 
such investment partnership, (ii) ValueAct Management LLC, as General Partner 
of ValueAct Management L.P., (iii) ValueAct Holdings, as the sole owner of 
the limited partnership interests of ValueAct Management L.P. and the 
membership interests of ValueAct Management LLC and as the majority owner of 
the membership interests of VA Partners I and (iv) ValueAct Holdings GP, as 
General Partner of ValueAct Holdings.  Shares reported as beneficially owned
by ValueAct Master Fund are also reported as beneficially owned by VA 
Partners I, as General Partner of ValueAct Master Fund.  VA Partners I,
ValueAct Management L.P., ValueAct Management LLC, ValueAct Holdings and 
ValueAct Holdings GP also, directly or indirectly, may own interests in one 



--------------------------                          -------------------------
CUSIP NO. 00724F101                                             Page 10 of 13
-----------------------------------------------------------------------------
or more than one of the partnerships from time to time.  Unless otherwise 
indicated below, by reason of such relationship ValueAct Master Fund is 
reported as having shared power to vote or to direct the vote, and shared 
power to dispose or direct the disposition of, such shares of Common Stock, 
with VA Partners I (only with respect to ValueAct Master Fund), ValueAct 
Management L.P., ValueAct Management LLC, ValueAct Holdings and ValueAct 
Holdings GP.  

         As of the date hereof, ValueAct Master Fund is the beneficial owner 
of 18,025,204 shares of Common Stock, representing approximately 9.9% of the 
Issuer's outstanding Common Stock (which shares may also be deemed to be 
beneficially owned by VA Partners I).  

        ValueAct Management L.P., ValueAct Management LLC, ValueAct Holdings 
and ValueAct Holdings GP may each be deemed the beneficial owner of an 
aggregate of 18,025,204 shares of Common Stock, representing approximately 
9.9% of the Issuer's outstanding Common Stock.  

       All percentages set forth in this Schedule 13D are based upon the
Issuer's reported 182,376,797 outstanding shares of Common Stock as 
reported by the Issuer on November 11, 2013.

       (c) In the 60 days prior to this filing, the Reporting Persons
purchased the following shares of Common Stock in the open market:

Reporting Person          Trade Date           Shares            Price/Share
----------------          ----------          ---------          -----------
ValueAct Master Fund      11/11/2013          13,400,000            $23.25


       (d) and (e)  Not applicable.


Item 6.     Contracts, Arrangements, Understandings or Relationships with
            Respect to Securities of the Issuer

       Other than as described elsewhere in this Report and as previously 
reported, the Reporting Persons have no understandings, arrangements, 
relationships or contracts relating to the Issuer's Common Stock which are 
required to be described hereunder.


Item 7.     Material to Be Filed as Exhibits

(1)	Joint Filing Agreement.
    

--------------------------                          -------------------------
CUSIP NO. 00724F101                                             Page 11 of 13
-----------------------------------------------------------------------------
                                  SIGNATURE
          After reasonable inquiry and to the best of his knowledge and 
belief, the undersigned certifies that the information set forth in this 
statement is true, complete and correct.  

                              POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears 
below on this Schedule 13D hereby constitutes and appoints Jeffrey W. Ubben, 
George F. Hamel, Jr., G. Mason Morfit and Allison Bennington, and each of 
them, with full power to act without the other, his or its true and lawful 
attorney-in-fact and agent, with full power of substitution and 
resubstitution, for him or it and in his or its name, place and stead, in any 
and all capacities (until revoked in writing) to sign any and all amendments 
to this Schedule 13D, and to file the same, with all exhibits thereto and 
other documents in connection therewith, with the Securities and Exchange 
Commission, granting unto said attorneys-in-fact and agents, and each of 
them, full power and authority to do and perform each and every act and thing 
requisite and necessary fully to all intents and purposes as he or it might 
or could do in person, thereby ratifying and confirming all that said
attorneys-in-fact and agents or any of them, or their or his substitute or 
substitutes, may lawfully do or cause to be done by virtue hereof.

                              ValueAct Capital Master Fund L.P., by 
                              VA Partners I, LLC, its General Partner

                              By:     /s/  George F. Hamel, Jr.  
                                --------------------------------------
Dated:  November 12, 2013     George F. Hamel, Jr., Chief Operating Officer

                              VA Partners I, LLC

                              By:    /s/  George F. Hamel, Jr.    
                                --------------------------------------
Dated:  November 12, 2013     George F. Hamel, Jr., Chief Operating Officer


                               ValueAct Capital Management, L.P., by
                               ValueAct Capital Management, LLC its
                               General Partner                             

                              By:    /s/  George F. Hamel, Jr.    
                                --------------------------------------
Dated:  November 12, 2013     George F. Hamel, Jr., Chief Operating Officer


                               ValueAct Capital Management, LLC         

                              By:    /s/  George F. Hamel, Jr.    
                                --------------------------------------
Dated:  November 12, 2013     George F. Hamel, Jr., Chief Operating Officer




--------------------------                          -------------------------
CUSIP NO. 00724F101                                             Page 12 of 13
-----------------------------------------------------------------------------


                                ValueAct Holdings, L.P., by 
                                ValueAct Holdings GP, LLC, its 
                                General Partner

                              By:    /s/  George F. Hamel, Jr.
                                --------------------------------------
Dated:  November 12, 2013     George F. Hamel, Jr., Chief Operating Officer


                                 ValueAct Holdings GP, LLC

                              By:    /s/  George F. Hamel, Jr.    
                                --------------------------------------
Dated:  November 12, 2013     George F. Hamel, Jr., Chief Operating Officer






--------------------------                          -------------------------
CUSIP NO. 00724F101                                             Page 13 of 13
-----------------------------------------------------------------------------
                                 Exhibit 1

                           JOINT FILING UNDERTAKING

The undersigned parties hereby agree that the Schedule 13D filed herewith 
(and any amendments thereto) relating to the Common Stock of Allison 
Transmission Holdings Inc., is being filed jointly on behalf of each of them 
with the Securities and Exchange Commission pursuant to Section 13(d) of the 
Securities Exchange Act of 1934, as amended.

                              ValueAct Capital Master Fund L.P., by 
                              VA Partners I, LLC, its General Partner

                              By:     /s/  George F. Hamel, Jr.  
                                --------------------------------------
Dated:  November 12, 2013     George F. Hamel, Jr., Chief Operating Officer

                              VA Partners I, LLC

                              By:    /s/  George F. Hamel, Jr.    
                                --------------------------------------
Dated:  November 12, 2013     George F. Hamel, Jr., Chief Operating Officer


                               ValueAct Capital Management, L.P., by
                               ValueAct Capital Management, LLC its
                               General Partner                             

                              By:    /s/  George F. Hamel, Jr.    
                                --------------------------------------
Dated:  November 12, 2013     George F. Hamel, Jr., Chief Operating Officer


                               ValueAct Capital Management, LLC         

                              By:    /s/  George F. Hamel, Jr.    
                                --------------------------------------
Dated:  November 12, 2013     George F. Hamel, Jr., Chief Operating Officer
     
                                ValueAct Holdings, L.P., by 
                                ValueAct Holdings GP, LLC, its 
                                General Partner

                              By:    /s/  George F. Hamel, Jr.
                                --------------------------------------
Dated:  November 12, 2013     George F. Hamel, Jr., Chief Operating Officer


                                 ValueAct Holdings GP, LLC

                              By:    /s/  George F. Hamel, Jr.    
                                --------------------------------------
Dated:  November 12, 2013     George F. Hamel, Jr., Chief Operating Officer