Hey guys, I did a search in both the GMC and Chev forums, and didn't have much luck... I also posted this in the GMC tech form, but I thought I'd try here too.
I have a 97 GMC Sierra Z71 with a 5.7L. At slow speedsduring braking and sometimes even in "park", I can hear a thumping noise coming from the transmission area. I have ruled out the common possibilities (U-joints, brakes, etc.) because it will do it when the tuck is stopped and in gear. I have had all the fluids changed and at the proper level (tranny, transfer case, and both front and rear differentials). Is my transmission or my transfer case on it's way out? It has to be something that is in motion when the truck isn't... I'm stumped! Any suggestions are greatly appreciated!