I have tried to pay more attention to my noise. Every time it happens I swear I have something in the bed of my truck moving. It does seem to be worse on cold days and or wet days. If i get a cold morning with fog in the air its the worse. It does it the worse when making tight turns. Happens when stopping and starting. Never at high speeds. Last night I noticed it was doing it consistently when I creeped forward in the parking lot with my foot slightly on the brake. I have also notice the noise happens with the turning of the drive train. The noise will happen, then stop, then happen again. It speeds up with the vehicle. So that eliminates shocks or bushings for me. If it was the differential I don't see the humidity in the air effecting it. I'm almost dead set it is in the brakes. With the rear of the truck it could be the disc brakes or the emergency brake. I wonder if their is a drag on one of the pads or shoes. Or as I mentioned before a stuck caliper pin. A slight drag on the shoes would explain why both temperature and wetness can effect it. Also why it normally goes away after driving a little bit. I also heard the exact same sound once in the right front drive train. Which again makes me wanna think brakes. I'm thinking about expecting the brakes on the truck myself. I wanna grease all the caliper pins and put some grease between the pads and calipers. Also check the e brake for any missing or bad springs. I had a 2000 Camaro once and every time I made a left turn from a dead stop their was a loud pop. The car was brand new. The dealer completely took apart the rear end checking the diff and drive train. After a month in the shop it never got fixed. They even called in a different tech from GM. A few weeks later I was working on the car to upgrade the brake pads and noticed one of the caliper pins in the front passenger side was seized and not moving. After freeing it up and greasing it the noise had stopped. Goes to show even though it was the front brakes even the main tech at the dealer swore it was in the rear end.