I drive my truck for about 15 miles at about 61 to 65 mph, when I get to that point the vibration starts in the front of the truck , no shake in the steering wheel, ,one theory was a valve tighting up and making the motor vibrate and vibrates to the front? I can let off and drive around 50mph and everything is ok? signed,Shakin In Temple Paul Smith www.23window.com/thezone H.B.B T.C.B.