it's a 9" MMC or KOYO , I'm not real sure on what plant the axle is built in, all I know is you can't break it or wear it out. Many came with LSD . Look for orange sticker in drivers door jam. The LSDs last forever, too.
Ratio is 4.625,,,that info and more is on a tag near radiator.

dave h.
'89 Raider V6 5spd;Aisin Hubs;; Gen2 LS: frt. brakes, rear coils;U.C.arms;R.trailing arms;idler arm; rear LSD axle w.disc brakes ;2 battery system for Dog's fan; relocated ECU; custom bumpers;J.Baker receiver;Conferr roofrack; t-bar crank.