Originally Posted by 94sport
Disconnect your u-joint from the rear yoke and then see if there is any play when trying to push or pull the yoke forward and back. If there is some movement you can try to tighten the yoke retaining nut just enough to eliminate the play. DO NOT JUST TIGHTEN THE NUT ALL THE WAY OR ELSE YOU MAY DAMAGE THE INTERNAL PARTS. Only enough to eliminate the forward & back movement. I just did this to mine yesterday while changing the pinon seal and and installing a sleeve over the yoke seal surface. Just got back today from a 100 mile trip with no leaks or humming.
Agreed ! Mine had the same problem. Noise at 30 and 60 mph. I inspected the driveshaft and replaced the ujoints, and tightened the yke nut in the process, not sure which one solved the problem, but I'd inspect the joints, and if they look solid, the yoke is the culprit!