I do believe those were made with the Oldsmobile Tornado engine and transmission. That make of car had front wheel drive which they incorporated into the GMC motorhome. A true classic.
My memory is foggy but I'm thinking a 461 cu in engine.
Someone will come along with more knowledge.
Jim and Carol Cooper with Oreo the Kitty
FAA ATC ret, VFW, AL, VVA, NRA
US Army Aviation, MACV Vietnam 65-66
2002 Journey DL 36, 3126 Cat 330hp