if you already have the 96 sierra, i think i'd try sell the diffs and get wide track or narrow track diffs if you want to keep standard diffs. but if you want to go 33s you might want to get bigger diffs like hilux or cruisers, but then you'd go 35s, and extend the wheelbase etc etc. Get a widetrack transfer case too, more common for parts/spares etc etc.
wow eh, sounds like you've got lots of work ahead
