Ok, here what is happening. I have a 1998 SR5 4X4, 5 speed manual trans.
When I float the gas pedal in fifth gear (2X4) I can feel a slight vibration in the driveline.This vibration does not occur in any other gear. I have looked at the ujoints and they seem tight. The center bearing for the driveshaft looks ok, but I can move it up and down about 1/2 inch. I have a 3 inch lift (springs and shocks) which I did 3 years ago. Any Ideas?