You will not find 9" brakes on an original A body 8 3/4" rear, they only came with 10x1 3/4" drums! You will also not find an A body 8 3/4" rear under a slant 6 car unless it was added, or ordered as an option. If it was ordered as an option, it would still have 10" brakes, not sure if the car would be automatically upgraded to all 10", but I believe that's what would happen!
