'08 Chevy 2500HD, 4dr, 6.0 L, 4x4, rear end noise

Very clean frame and undercarriage, one spot on rust on one bedside, and one spot on a rear rocker--but the rest of the truck looks like it came from TX.  No rear seat (previous owner got rid of it for work boxes.  AC is cold, 4x4 works, 6L engine sounds great, and the transmission shifts well.  The rear end is making noise (not as bad if you are keeping your foot on the gas).  Good title.  Great work truck.  Located near Lambert Airport.  C A L L three one four-three nine seven, seven two seven eight.