You will have to swap the entire rear end, as NOTHING but the center section interchanges between those two rears. I'm not surprized your E-Body has that rear, as it is a DIRECT bolt in for a 1957-1960 Mopar and most all the E-body rears are sought after for these early 8 3/4 rears....
The Axles, seals, bearings, etc. are all smaller and set up with shims...