Truck Tranny Question

I want to upgrade my rearend from a 7.25 to a stronger one. A local guy has a rearend he has pulled from a pickup with a 318. Will a truck rearend work in my A-body Dart? Or will I need to modify something? My car has a 318 with a 904 trans. It was originally a slant 6 car with the wimpy rearend and I want to put a beefy rearend up underneath it.

Thanks