Called an add in the paper the other day for a 68 Cutlass 455 turbo 400 12 bolt posi. I'm no Oldsmobile expert, but this guy said the rear was not the same as the Chevelles. He said they used a 12 bolt corporate rear. I thought all A-bodies were the same. I have a 68 Olds Delta Custom in the back forty, 455 400 12 bolt, and the diff looks identical as the one in my 67 SS. Any experts to shed some light? I know there is a one inch differance in the width between 67 and 68 - 72.

Olds 12 bolt is really a 10 bolt, 12 bolts on the cover but 10 on the ring gear. Try a search, lots of info here.

Did a search, lots of reading, now I know alot more.Including the fact that the rear in my 68 delta custom is in fact a Chevy 12 bolt. it has the groove on the cover.No reason to believe it has ever been changed.These cars are both Canadian
cars, hmmmm, wonder if that makes a differance?