I have a 04 sierra, 5.3 automatic that has a clunk in the driveline. This noise occurs when pulling out from a stop. It also occurs when shifting into and out of second gear. This is also louder , like a clang when downshifting into second under a load when I am towing. My dealer has been no help, can you help me?

sounds like a U-joint with too much play.

Sounds like the slip yolk, GM is notorious for those. My dad had to have it replaced in his truck, and I recently had the same problem with my yukon. As a temporary fix, they can be greased or lubed up. This happens when the suspension preloads and lifts up the rear end, then when you take off and it drops, the slip yolk snaps back into place.

Edited March 8, 200718 yr by schuby87

I'd say either a problem with the yoke, or the U-joint right there at the transmission is probably shot.