Oh were you talking about the WHOLE rear end or just the carrier assembly? I assumed you were talking about the carrier assembly.
TO echo Roy's answer, yes, the 8 3/4 A body rear will bolt in. You will have to shorten the drive shaft. Also, the later 8 1/4 rear end is a bolt in swap. Drive shortening also required. BUT the other thing there is, with the 8 1/4 you have the 4.5" bolt pattern instead of the 4". So you have to make the decision if you want to run two bolt pattern wheels, change the rear to 4" or change the front to 4.5".
