Check the linkage to see if it needs any adjustment. Check the fluid level in the case. Change fluid if necessary. Always do the free and cheap stuff first.
Unless you are doing some major work on it, you aren't going to see much of a performance gain with 1 system vs another on a 4.0 jeep. Just get what sounds good to you.
The best tires we have had on the TJ since we have owned it. (Late 97) We strictly use at's because our jeeps are 90% street with dirt trails on my property and small farm use the only off roading. These work great in the rain on the street. They hydroplane the least. They are quiet. They have good grip in the dirt.
I like them enough to put a set on the mj as well. They handle well too.
we have had big o bigfoots, procomp at's and bfg at/ko's. Like these the best.
and as a bonus cooper is one of the few manufacturers that still makes them in the good ol' U S of A!
Since i took over the truck from my son back in january 2011, i estimate less than $3k. If you count the purchase price when i bought it from my father in law for my son and fixing it after he totaled it twice,, then i would say about $5k or so.
Kh, have you started the truck since this? Is it fixed? I am working on all the ground refreshes now. I seem to have pretty good grounds from what i can tell though.