recently every time i switch my truck into reverse i hear a clunk, it sounds like its coming from the rear end and i have no idea what it could be also whenever i go over a bump i also hear a loud crash like something is moving in the back bed i don't know if this is due to the same issue or not.

 

I would get under there and check universal joints, leaf springs, and even shocks. My brother has a Tahoe that was making similar sounds and it ended up being one of the shocks had become loose and the rubber bushing was gone. It made a hell of a racket.