If you hear a loud bang like you ran over something or like you kicked up a rock, well congratulations, the pin on driver side axle shaft has snapped, and at that point you are currently contaminating your transmission. In about 400-700 miles you will start to experience the joy of transmission slippage. To verify this event, just look at the trans fluid. Good trans fluid looks like cranberry juice. Contaminated fluid will look like greyish black and it will stink!! What is happening inside the transfer case, which contains a separate fluid type (Totally Different Fluid); it's now being pumped into the transmission fluid. The poorly designed GM transmission doesn't like this. Fluid is being allowed in by the missing/broken axle shaft pin. (Taken from another post)

This past weekend I have experienced a bang (not so loud)or like I kicked up some gravel in my wheel well. My transmission fluid still looks good and shifting is good as well. If there is merit into the above post, how would I fix the pin that snapped. What is that pin? Reading all the posts it only mentions the clip. In VADIS does not show a pin. Can anyone explain this? Ever since this happened I hear a low toned grinding or rubbing noise, something like a worn brake pad (I checked my pads and they are still thick). When I accelerate it goes away, when I let off the gas I can hear it and when I coast. When I step on the brakes it goes away. I only hear it at about 25MPH and above. My axle boots are all intact. I plan to jack up the vehicle and listen to it where I don't have wind or road noise or listen to it without the axles...I'm stumped!