IIRC Alex Phifer used to run a GSL-SE diff for a little while. It's probably a good setup.
We are doing three 8.8's for diferent customers at my shop at the moment.
all the core parts usually run about $150.
The 8.8, modded so that it simply bolts into all existing AE86 chassis points is a bit less than 1k. You need to have a shop mod the driveshaft a bit (about $100) and choose what kind of internals you want (spool, LSD, Locker, ect- 200-500), and the axles. (varies)
It's not cheap but it works, the corolla market is into doing things on a budget or this would be a lot more popular. It's for those that want the strength if they need it. These customers right now are all drifting, road racing, and drag racing to win.
this setup is good for about 400ftlbs of Tq
Esoteric Performance... don't compromise.