Took truck in for a rattling noise behind the rear seats. Tech was able to hear the noise and determined that it MIGHT be the tonneau cover on the back of the truck. The GM Accessory cover was installed at the dealership by certified GM accessory experts where the vehicle was purchased. Frenchies was not able to fix the problem and asked me to work with the original dealership who installed the cover. Good service people to work with, but GM is certainly not focused on customer satisfaction.