Which rear is this.

The factory starting installing 8.75's in the later part of the 65 model year in cars with the 273/235 4 speed combos as those combos were just trashing the standard 7.25s. 8.75s were see more in 66 and much more later years. An 8.75 installed in a 64 or earlier A body was done by an owner. As someone mentioned, they were even seen with slant 6s. I parted out a 71 slant 6/904 mordoor that had Kelsey Hayes disc brakes and 8.75 - the owner wanted HD components for towing but with a slant's supposed economy :wack:.