Thanks for the great advice. I am not real good at this stuff but I can work my way through most things. I think I will give it a shot. A book you say... been a while .. I think Ill look online. If you know of any good links please send them my way.

I will go synthetic if you say its going to be much better. If I were to change gears what would you recommend. I road drive this boy, its on 33s and I would love to get better milage. Would I have to also change the front then? Again thanks for your wisdom...

 

You would need to match the front to the rear for 4wd. I switched to 410 with my 2wd 5.0 AOD on 31's. It seems to be right on the mark for daily LA traffic on the freeway. If I were primarily off road id go higher ratio but on the road i think it would rev to high. Not sure how much difference 2" of tire would make.

 

new tire size
Old tire size X axle ratio = new axle ratio

That's my math trick, if you had 30" tires, and 3.00 axle gears, 35/30 multiply by 3 and get 3.5 so new ratio should be about 3.50 , or higher for the same performance as with the old tires, a little higher ratio will help acceleration because bigger tires are heavier, at least in theory.

 

Unless your just bored out of your mind or have more money than sense just change the seal as sugested by 5rangers if it aint brocken dont fixit just change the seal inspect the gears clean it out and fill with a good quality synthetic 75/140 oil and if you have a positrack dont forget to add the friction modifier. setting up a rear gear is not a job for a novice and if done wrong can get expensive.

 

One thing no one has mentioned, the crush bearing on the pinion is not reusable. Therefore you can't get the proper preload by changing the seal. You can get pretty close with rangers method, however it will be a bit off. If you torque to the proper preload you will be a bit deeper on the backlash. If you simply change the crush bearing and set the proper backlash there should be no need to change the side shim. But as I said you can get pretty close with rangers method. You may end up with a little noise or looseness. Worst case is a shortened gear or bearing life. But most likely you won't notice. However like I said, learning to do the job yourself gives you a sense of pride and the ability to do it again. If you can overhaul an engine there is no reason you can't set up a rear end.