There is a clunking in the rear of my Yukon Denali and I'm about to sell it. So far, I've replaced - Shocks, Compressor, Sway Bar bushings and links, Spring insulators, pan hard bar, checked brakes, rear window and latch, both rear seats, checked lug nuts, hitch and cover. I've crawled under and lubed every moving point. I've zip tied the 3 aluminum lines that run underneath from front to back. It is driving me absolutely bonkers. PLEASE HELP!