A-Body 8-3/4 Narrowed Rearend

Here's a good reference for rear lengths. Housing, axle and total length/widths

http://www.moparts.org/Tech/Archive/axle/16.html

A body 8.75 only had one brake package, SBP, so housing lengths wouldn't vary from the factory lengths listing in the link. My guess they are SBP axles with bolt patterns in them. You can't shorten an 8.75 too much in an A with stock spring location because the U-bolts will start biting into the housing ends.