Nice thing about those Vans is they often have a build sticker on the underside of the hood that will clearly state rear end type, gear ratio, and brake size. Also true for transmission type and engine family. Sticker reflects factory built condition and sometimes things get changed out over the years so you can't take it as gospel, but in my experience it usually is accurate. Most van owners aren't in a big hurry to modify and just repair and maintain so sticker equipment list is usually what's there. It can be a bugger to pull a van engine at Pick a Part. No room to go through the side door and, at least with earlier vans, they were not designed to come out the front, though it can be done. I had to build an extension for boom/lift arm on my engine hoist to do it on an '02 B3500. Even doing that only allowed me to install the shortblock (no heads/intake) through the front. You'd never be able to do it with the rolling "A" frame lifts most yards supply. I agree with many others that modifying one of these rears to fit your car/change the bolt patterns, etc will be more costly than buying an 8.25 or 8.75 rear for your "A" body.