another problem i am having is that when i am in gear at a low rpm (say 2nd at low speeds accelerating) i hear gear chatter coming from the rear. I am about to put in 3.90's but since its going to be apart is there anything i can do to fix this...thanks, Brad

 

could be gears are worn and eat themselves up or posi is worn and the clutchs have no friction material left. Either way its hard to tell over the internet what that one might be.