73 Dart 3rd member swap

Well it would help if we knew what is in your Dart now.

In 73 any disc brake car already had the big bolt pattern and the 7 1/4 rear end had the 3 inch tubes and brakes that will swap onto the 8 3/4 so you only really need the axles with the big bolt pattern. If you are going to redrill the the axles and drums then you can use all the small bolt pattern stuff but then you end up with drums that you can't just go to the local parts store for.