need some help on my 07 NBS gotta noise.

ill try to explain this the best i can. there is some type of clunking popping noise coming from the back of my truck.. its like where the drums are on the rear.. the wheels are tight.. but its very aggrivating.. i thought it may be loose u- bolts since i put a bigger block in the rear.. but i dont think thats it..also sound like it could be coming from the leaf springs.. it does it alot when i am kinda flexing into a driveway or backing up just like a clunk clunk pretty noisy or if im on a bumpy dirt road or something.. it doesnt do it just driving slowly forward it only seems like it does it when flexing like i said or bumpy road.. Also when i push on the bed from side to side it sounds like the clunk comes from those drums but when in the truck sounds like it comes from right under the back seat

sounds like the leaf springs are dry. I had the same issue on the 2007 CC classic. I had to jack the truck up by the frame, spread the leaves apart with a pry bar and squirted some axle grease between them. The springs got really quiet after that. There used to be companies that made leather "corsettes" for spring packs. You'd grease the spring packs up really good and then but a rawhide leather wrap around them and lace them up tight. It kept the grease in and killed any noise. Never had a rust issue and looked cool as hell. I know, I'm dating myself but you can't argue with what works.

not that.. i have aftermarket side rails? but it never has done it until now it also is staying around 20 degrees out here just started it when the cold front came in.. could it be a body mount pop maybe? i guess ill remove and see. Cant think of anything else.. what would be in the drums in the rear when i push on the bed hard from left to right that makes a pretty loud clunk?

Exhaust maybe? One of my exhaust hangers hits the frame on bumpy roads or sharp turns.

i checked those.. this thing makes me sweat bullets.. its more of a thud or something comin from middle of truck it sounds.. maybe in rear.. from the outside sounds like something in the drums but from inside sounds like a thud

You ask us for opinions but then when we offer them you say no its not that it sounds like the drums. Well if it sounds like the drums then pull them aprat and inspect them.

Take your aftermarket step bars off. Go drive around? Does the sound still occur?

If so, then you are having issues with your lift blocks in the back.

just eliminating things it could be so nobody else's opinion is the same. im going now to pull the side steps off.. maybe thats It... ill let yall know later thanks for the help.