8 3/4 rear sbp to bbp help needed plz

Original A-body axles must be PLUG WELDED and re-faced in addition to being re-drilled.

5 x 4.5" bolt pattern A-body axles set up for standard B/C/E body brakes increase the track-width 1/4" per side.

This is usually a non issue, as common 15" Mopar spec wheels work nicely with the combination (15 x 7" with 4.25 BS, 15 x 8 with 4.5" BS).

BTW, a new 5 x 4.5" A-body axle pkg runs $295 pair, assembled:

http://www.doctordiff.com/axle-package-stock-length-mopar-5x4-1-2-bolt-pattern.html