I'm not sure about what sizes or what would all be necessary to make one fit, but has anyone ever thought about getting one of the old 8.5" 10 bolts(not 7.5"... the weak ones" from some older car(I know they were equipped in second gen Camaros, I believe some of the later second gens) and making it work? You can find beat up second gens for cheap, and you could just take the rear end out to put into your 4th gen...

eh?

 

They were used in GNs, too, among other vehicles. My Blazer came from the factory with an 8.5" 10-bolt 3.73 Eaton posi rear.

It would need a lot of custom work, fabbing mounts, etc. Here's a link to a thread discussing the 8.5" that might be some good reading.