The 75-A-chassis seat (with or without chassis seat back) was announced in the September 3, 1931 Indianapolis Service Letter. It consisted of the standard commercial front end, open cab floor assembly, heel board/riser, and seat cushion.

With a seat back included the open cab back and seat backrest were also provided. So, the 75-A-chassis seat was a 76-B open cab without a top, windshield, or doors.