after my lift and upgrade to 35's I ran with the stock 3.21 gears for a while (6 speed manual trans). UGH!!! was really unacceptable even as a daily driver. So, I recently had the guys at 4WD Parts in Cleveland, OH install a new set of G2 4.88 gears and Eaton TrueTrac lockers. Based the awesome gear chart below.

My two cents. I wish I would have gone with 4.56 gears. My Jeep is truly a daily driver. I don't go crawling as a general rule. It's really more of a hunting vehicle. Driving up and down Interstate 79 attempting to maintain highway speed 75 MPH is horrible (3000 plus RPM's) in sixth gear, watching the fuel gauge race to the left almost as fast as my tach.

OK, so I digress. My real question is my differential. IT"S HOT. Really HOT!!! Not quite as hot as the muffler, but damn close. You almost cant hold your hand to it after driving. Is this normal??? Any thoughts or input on the topic would be greatly appreciated.

 

when i had my 4.88s done, they were hot for the my trip home, after that its fine. the rear gears will likely be hotter than the front because there is actually a load being placed on the gears at all times, so dont freak out.

 

With a trailer hooked to my f350 hauling 10k, the rear is warm to the touch. A jeep with relatively no load should not be that hot! Just my 2cents