My truck (2008 1500 5.3 regular cab) has developed what I would term a 'thud' or 'clunk' from the driveline while sitting at a red light. It does not do it on a stop and go like a stop sign, just after sitting 10+ second or so at a stop light with my foot on the brake. I don't know if it is a u-joint but I think I may have read something about the output shaft on the transmission? Would this still be covered under the drive train warranty?

 

Pull the driveline, clean the splines, and apply some synthetic grease to the splines. Takes 30 minutes, and will probably fix it.

 

+1 had the same on my 08 rcsb 4.8. Dirt gets in there and binds it up so the driveshaft doesn't slip bank in. The thud is it doing so forcefully

 

Would this need of grease on the spline also answer why i get the same thud, or clunk, when going from drive, stop then reverse. Because i will get the same symptom as the OP at a stop light but also from shifting from forward to reverse. same thing?