Just got my 04 XLT SCAB back from dealer, it seems that the rear window is held in place with screws, and a couple of mine were broken, causing the window to shift ever so slightly with the body movement, and thus that nerve wracking squeak that some of us have endured. The fix for the broken screws is a new window and seal. I am glad to get out of the Chevy truck they loaned me and back into my truck. Dealer had it for 4 days. Took her for a long drive, so far so good.

 

Glad to hear that the dealership did their job! Thanks for posting your findings!