I didn’t take it to the dealer, I dropped the headliner and put a piece of sound deadening material between the panel and the rib.I have that same rattle. Sounds like it's coming from my rear passenger roof panel. Only hear it when certain bass tones come on or if someone pulls up next to me at a stoplight with subs & there basd is really thumping. So what did the dealership do about it ?
Tap the roof panel from outside of the truck in a few spots and see where the rattle is.