[dsraven]

ok, stock suspension but what about the driveline?
post some under hood pics
sounds like a diesel with a standard trans, what do the engine mounts look like?what do the clearances look like around fan, manifolds, exh pipe, mufflers etc. an engine part rubbing a frame part could sound like that. it kinda uses the frame like a tuning fork.
can you have a buddy torque up the driveline, like doing a brake stand but not fully releasing the clutch or moving the truck, just to see how much the engine and driveline move. do this in forward and reverse.slide under it when it cools down and look for shiny spots at tight clearance areas. if in doubt mark the tight spots with something removeable, like a grease pencil or kids' wax crayon. then go for a ride and redo the noise. come back and check to see if there are marks in the crayon. leave it in gear, hood up with some eyes on the engine, rock the truck back and forth to see if the engine rubs anything. can you reproduce the noise when not moving, torque the driveline in forward and reverse and listen/look
it sounds like a tire rubbing but obviously you have checked that. driveshaft rubbing would be obvious as well. does it have a 2 piece driveshaft, check the centre bearing? trans and engine mounts not bottoming out? fan not rubbing the shroud? rear axle C clips not allowing lateral movement of axle? again, post some pics with detail of under hood and driveline. maybe we can see something you didn't