Another ford 8.8 question

Hello,
I picked up a ford 8.8 this winter. Actually came out of a lincoln mark 7. Appears to measure 61 inches backing plate to backing plate. Disc brake, posi traction, and axles are equal lenght . Will this fit under my 72 valiant?
Obviously i know perches, and u bolts / shock plates are different. But the actual width close enough to work?