I ran the 33" MT's on mine with stock gearing and it did fine. If your going to upgrade, search for the 4.77's out of a '89 Isuzu Trooper RS, some 4dr Trooper's in that time frame came with them if they had the big tire package but they will be very hard to verify without pulling the diffs. If you don't do any extreme wheeling and don't travel up steep inclines on a daily basis, I'd keep the stock gears.