Valiant? (I'm embarrased to admit I don't know)

Review the movie "My Cousin Vinny." Comedy with the then hot-as-women-get Marissa Tomei Centered on reckless driving tire marks and the incorrect identification, because of whether/ or not the tire marks exhibited the changing tire track of an IRS

GM in those days, if nothing else, was "unique"

Chev had The Corvair, unique all in itself

Ponch had the Tempest, and as mentioned the thing initially used an IRS and transaxle, a "flex" drivesahft Porche 914 style, and a "slant 4" made from one of their V8's

Bleack had the 225 V6--Actually 198, and they offered the same 215 V8 the first year

Olds (F-85) had the little aluminum 215 V8 which they later sold to Rover and who used the thing for YEARS in their Land Rovers.

Neither Olds nor Buick were IRS they had conventional solid rear axles

Later on, Ponch offered a few Tempests with the rare OHC 6, but most I've seen were pushrod engines