My truck started shaking when I am slowing down to stop. I am pretty sure its coming from the rear of the truck. It only starts it at about 30 mph and does it until I get stopped. It feels like I am driving over rumble strips. I thought maybe it was the rotors that needed to be turned. So I had that done yesterday, and it still does it. Anyone else have this problem? Its a 03 Dually. Now I am starting to think its something inside the rear. Any help is appreciated.