I just recently started hearing a squeal coming from somewhere to the rear of my cab but in front of my rear wheels and had my friend listen to it. The noise only ccurs when I am in drive. It doesn't occur when I am in reverse or rolling in neutral. It continues through all speeds and gets louder when starting or stopping. When laying off the acclerator, the sound stops when traveling at 45 mph. He believes it is my universal joints and I talked with my friend that has a 01 f150 2wheel drive and he heard similair sounds when his u joints went out. any ideas?