I have a "clunk" in the drivetrain of my '99 4x4 short bed when shifting in and out of gear or letting off the gas. Transmission is a newly rebuilt DTT. Rear end is recently inspected with little or no wear. We even replaced a couple of bearings just in case. U-joints are tight. Don't know what else to check. Could it be the transfer case? How would I check? Truck is at 108,000 miles.