"Clunk" in the drive train on 2005 GMC Sierra 1500

When I start out from a stop, there is a "clunk" in the drive train. I don't know if it is in the rear-end, the 4WD transfer case or something else. When a friend rode with me the first time, he asked what I had rolling around in the bed each time we started out. Anyone else had the issue?

Asked by for the 2005 GMC Sierra 1500
You'll need to have this looked at to know what it might be, there are drive shaft, engine/transmission mounts and suspension possibilities, but this really needs to be experienced to know what it might be.
2 answers 1 comment
Same issue here with 2005 1500HD 6.0L
I have not found out what the problem is yet, fixin to take to the Garage.
I took mine to a garage and while they did a thorough once over, they could not find anything that looked like other than normal 'wear and tear'. I have heard about GMC's have slopping rear-ends and don't know if this is something I'll just have to live with or not. Please let me know what the garage has to say.