Will a 1970 A-body O-type 12 bolt rear replacing a 1971 Cutlass Supreme 8.5 Corporate rear require any changes? I've read that the diveshaft will need to be changed, but I've also read info that states that it would be a direct swap with not alterations.

 

Driveshaft could need to be about 1 longer...BUT you may not have an original driveshaft in the car after this many years.
BUT YES, normally and swap with a 8.5 the driveshaft will need a lengthening or shortening depending on if you are swapping it in or out with another NON 8.5 Corp 71 72 rear.
Jim
JD race

 

Thank you Jim! I appreciate your feedback, your expertise,and salient contribution to this great forum