Diplomat calipers would most likely be rear hung. The R body cars got the larger 11.75 rotors. FMJ usually got the smaller 11 inch. Or perhaps FMJ only got the 11 inch rotors, I really don't know for sure. But when I used to do disc brake swaps I would search for R body cars since they had the larger rotors. The knuckles off of the the FMJ cars are good for disc brake swaps. They are taller than the A body knuckles and they are lighter.