I have the same truck. Bought it used from a dealer. The truck has been running and driving great. I opted to purchase an extended warranty as history for the vehicle was not available. Now, I have the same problem. Dealer said is was the transfer case and they replaced it. The truck was taken for a drive and the grinding noise was not fixed...not the transfer case. So now, the torque converter is being replaced. I would appreciate any updates of fixes for this problem.