7 1/4 tube length

Sounds like a B body rear, with a little work and proper backspace wheels, you could probably use it the way it is.

IF you cut it see post #2.

You will also need new axles as the B body axles can't be cut and re-splined for the A rear. You would need new ones or find a set of C body axles to cut and spline.

Search Mopar Muscle for an article called "Back End Boogie". They put a B rear in a Dart and it worked.