I tried searching past threads and could not really locate anything that sounded the same. Yesterday I was driving, about 50 mph, and heard a scraping noise that sounded like I was dragging a chain link fence. After about one minute there was a loud thunk and the noise went away. No lights came on the dash and acceleration was not affected. Any ideas? Thanks.

 

I dont know if this helps at all but I had an 04 for a test drive with the electronic t-case and it did the same thing once in a while. Turns out it was the four wheel drive trying to engage. Never turned on a light on the dash, but it kind of made me shy away from the truck. Talking to other people I heard of a few other cases where it happened as well. Some dealer reprogramming cleared it up.

 

Thanks, it happened again today and the thunk/thump noise sure sounds like it's coming from the drivetrain. Thanks for your reply.