My advice is to go to LKQ and look for M body cars.
I think there was a Diplomat at one of them in the Tampa/Clearwater area.
I have a rear out of my '73 duster ,minus brakes. it will need a ring and pinion , it broke a tooth off the ring gear . Located in Holiday Fl.
Might get some 15x7 5 on 4.5 steelies from the same car.