I have a 2001 Xj with 3.5 RE lift, 31 inch tires. 242 transfer case with ironrock hack n tap and a front driveshaft i am using for the rear. The driveshaft was rebuilt with all need u joints before i put it in. 8.8 rear end swap just went in but i had the noise before when i had a 8.25. So it should not be rear end related. I have a quick grind or cluck noise on deceleration at any speed over 20 mph. It is not a continuous noise just a quick pop.

 

Anybody?

 

I have this aswell. I suspect its the transmission mount. Get under and kind of move the t case and x member with your hands and see if you hear the noise. I havent got around to replace and I left for college without my jeep so I dont have evidence.