I have an 06 4wd with 165K. The first time you take off from a stop after starting the truck I get a groan/grind noise with a little vibration feeling from the front end. It happens in the first 25 feet of rolling in forward or reverse. Only happens the first time, after that you can come to stop and take off and no noise or vibration. You can shut the truck off, turn back on, and it will replicate the same groan/grind/vibration noise. I recently had one of the front actuators replaced, I jacked up the truck and verified that both half shafts are not spinning in 2wd, so the IWE/vacuum system seems to be working correctly, being that you have to shut the truck off to duplicate the noise I thought maybe it was a vacuum problem. I have had it to a couple shops and neither seems to know what is going on, any help would be appreciated before I have to take it to the dealership. Thanks!