If I were having this problem, and I thought that it had anything to do with my driveshaft (and I think it does)...I would give the folks over at Tom Woods (www.4xshaft.com or 1-877-4xShaft -- 1-877-497-4238) a call. They know a bunch about these kinds of problems.

Measure the shaft you currently have. Give Tom a call and give them your information: what engine, trans, xfer case, SYE, rearend and current shaft length. Ask what length shaft you should have for your application, compare that to what is currently in your jeep. That will answer a lot of questions. There are many reputable driveshaft vendors out there; however, I've had nothing but good luck w/ Toms stuff.

Ed