Searched through some other threads and didn't find anything that matches my symptoms. It's an 05 Silverado 3500 DRW 4x4. The only time I notice it is when going slow, as in walking speed, and either barely on the gas or at idle. It sounds like a solid clunk with about every rotation of the tire. I've jacked the truck up and ran it on jack stands, no noise. I've turned the wheels by hand on jack stands, no noise. I've removed the rear wheels to make sure there wasn't anything trapped. Crawled under the truck and the u-joints seem fine, even greased them while I was under there.
Next on the list is to pull the hubs to see if maybe something in the parking brake has failed? Any more suggestions? It isn't spring related as I know there have been lots of issues around that. It doesn't seem to get better or worse when I turn. There is no vibration or noise going down the hwy. You can't really feel the clunk unless you are really really paying attention and the surface is smooth.