When I start or stop, I get a loud thunk from area where transfer case is

[goblues38]

to me it sounds like the transfer case is shifting location or sliding on its mounts as slack is added or removed from the drive line.

Or maybe the exhaust system is sliding back and forward.

I have crawled under the truck and find no obvious things out of sorts. Any idea what to check, or have checked if I go to a dealer or shop?

 

[GordoJay]

U joints?

 

[goblues38]

U joints?

Did the slip yoke geese repair and it fixed it.