Exhibit 99.6
Cawley, Gillespie & Associates, Inc.
petroleum consultants
| 6500 RIVER PLACE BLVD, SUITE 3-200 | 306 WEST SEVENTH STREET, SUITE 302 | 1000 LOUISIANA STREET, SUITE 1900 |
| AUSTIN, TEXAS 78730-1111 | FORT WORTH, TEXAS 76102-4987 | HOUSTON, TEXAS 77002-5008 |
| 512-249-7000 | 817- 336-2461 | 713-651-9944 |
www.cgaus.com
Consent of Cawley, Gillespie & Associates, Inc.
March 27, 2026
Permian Basin Royalty Trust
Argent Trust Company
3838 Oak Lawn Avenue, Suite 1720
Dallas, Texas 75219
Ladies and Gentlemen:
Cawley, Gillespie & Associates, Inc., hereby consents to the use of the oil and gas reserve information in the Permian Basin Royalty Trust Securities and Exchange Commission Form 10-K for the year ending December 31, 2025 and in the Permian Basin Royalty Trust Annual Report for the year ending December 31, 2025, based on reserve reports dated February 26, 2026, prepared by Cawley, Gillespie & Associates, Inc.
| Submitted, | |
| Cawley, Gillespie & Associates, Inc. | |
| Texas Registered Engineering Firm F-693 | |
| |
| J. Zane Meekins, P. E | |
| Executive Vice President |