Segment Information (Details) $ in Thousands	3 Months Ended	9 Months Ended
Jun. 27, 2026 USD ($)	Jun. 28, 2025 USD ($)	Jun. 27, 2026 USD ($) segment	Jun. 28, 2025 USD ($)
Segment Reporting Information [Line Items]
Number of Operating Segments \| segment			2
Number of Reportable Segments \| segment			2
Net sales	$ 517,160	$ 398,011	$ 1,202,879	$ 1,070,734
Cost of goods sold	413,786	312,083	957,629	853,635
Gross profit	103,374	85,928	245,250	217,099
U.S.
Segment Reporting Information [Line Items]
Net sales	472,300	352,715	1,067,750	939,946
Canada
Segment Reporting Information [Line Items]
Net sales	44,749	45,022	134,884	129,096
Rest of world
Segment Reporting Information [Line Items]
Net sales	111	274	245	1,692
Operating Segments
Segment Reporting Information [Line Items]
Gross profit	103,374	85,928	245,250	217,099
Operating Segments \| Bus
Segment Reporting Information [Line Items]
Net sales	491,696	372,240	1,124,445	993,099
Cost of goods sold	400,623	299,029	917,858	815,082
Gross profit	91,073	73,211	206,587	178,017
Operating Segments \| Parts
Segment Reporting Information [Line Items]
Net sales	25,464	25,771	78,434	77,635
Cost of goods sold	13,163	13,054	39,771	38,553
Gross profit	12,301	$ 12,717	38,663	39,082
Intersegment Eliminations \| Parts
Segment Reporting Information [Line Items]
Net sales	$ 1,600		$ 4,200	$ 5,400

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