I had a 2015.5 Yukon XL Denali. Had a problem with the transmission so GMC did a exchange and now I have a 2016 Yukon XL Denali. Both vehicles had a high pitch squeak/noise. It is driving me crazy. It is not loud. I can barely hear it but it is just loud enough to bug me. I think it is when I hit small bumps or vibrations but I am not 100% sure. I notice it at lower speeds driving around the city. It doesn't seem to be coming from the engine area. Maybe from the front seats back. Any ideas? Anybody else have something similar?