B-Body 8 3/4 in a A-Body
I used to have a 71 Duster w/ 68' B-body Dana and a 75 Dart Sport w/ B-body 8 3/4. It's actually pretty common to use a pre 71' B-body rear in A-bodies. B-body rears are easy to find and a hell of a lot cheaper than an A-body rears with aftermarket axles when purchased used.