2001 Ford XLT 4X4 4.6 automatic 80,000miles. Has anyone had this problem or can tell me why this truck would not shift into third gear the other day until I came to a complete stop. After that, it seemed to shift OK. I have had a noise coming from what seems to be the rear. This happens when I get on it, the noise is just before the truck shifts. The sound is hard to describe but sounds hollow vibration, like blowing into a pipe. The transmission shop said they cannot find a problem, or any codes.