I have the 3.0L Diesel engine with the 8-speed automatic transmission.

There is a very obvious clunk that comes from the drivetrain when the truck is in 4x4 Lock or 4x4 Auto. The clunk only happens while the vehicle is coming to a stop from a speed in excess of about 30 KM/Hr and can be sometimes be felt in the 3-2 downshift and is always felt in the 2-1 downshift.

Dealership tells me this is somewhat normal, but wouldn't let me test drive a vehicle on the lot to prove their argument. I went to another dealership posing as a customer and "test drove" a few trucks and sure enough there was no clunking present.

I suspect a loose CV Joint or universal joint but haven't been able to find anything as of yet.