Cars you can grab from to replace the entire housing without modifiation?
Another g body
Cars to Just pull the center section from? Depends what you want.
You can get a gov lock 7.5 (don't do it, a good way to make your 7.5 even weaker), an auburn cone style (not rebuildable), and eaton, a torsen out of a 4th gen camaro and many more. Anything newer than 1988 will be 28 splines, and yours is currently a 26 so that is something to think about. I ended up snagging a set of stock GN 28 spline axles for cheap
on ebay. That allowed me to run the 28 spline 7.5 carrier I got for free. 26 spline posi's can be hard to come by, 28's are usually a little cheaper (used) from what i've seen. You'll also need to consider what gear ratio you want to run so you pick the right series carrier. You can pull a center section from almost any GM vehicle that came with a 7.5 and it will drop right into your housing. Blazers, S10's, Camaro/Firebird, etc.
You can also use a fox body mustang 8.8 with a trick chassis swap kit, or even a g body specific 9".
But I also agree, a big thing to consider is why you are swapping rear ends, and what the cars purpose is.