Click on this Diff ID
to find out what diff you have.
As far as lift, 4" will clear the 33" tires. Actually, I have a sliiiiiiiight bit of rubbing on the rear of the rear fender wells. But I've heard this is to be expected.
85 CJ7 4.0L/SM465/Dana300/AMC20/Dana30, MPFI,154K miles - 33" 12.5's Pro Comp MT's, one piece axles, Detroit Softlocker rear, Lock Rite front, Warn Hubs, 4.56 R&P, 4" BDS lift, Warn x8000i, Warn winch guard, Hi-Lift, Tuffy console, Four X Dr. rocker guards, Rock Hard sport cage, Kilby OBA with 1.75 gal tank and York 10.3cc compressor, Tube fenders by GenRight Offroad, Fabricated rear bumper and tire carrier.