B body rear brakes onto A body axle

cut the spring pads off your B-body 8 3/4, move them to 43" C-C, and put it back in the car.

I don't recommend that anyone use an A-body axle in a Duster/Demon/Dart Sport. Just a bunch of headaches for most of us. I have a 68 b-body axle in mine, and we just put a 1965 B-body axle in my friend's 1971 Demon. Took about 3 hours to move the spring pads on his and we were done. Angle finder, grinder, and a 220V welder is all you need.