2nd Gen Non-Engine/Transmission Need U-Joint help

[TMills]

I need help diagnosing a u-joint problem (I think). I have had my tires rotated and balanced, but it did not help. I get a small vibration around 55mph and then it comes on strong at 65-75. It feels like my wheels are about to fall off. How can I tell if it is one of the joints in the front axle or if it on one of the driveshafts? I don't want to take everything apart just to check a joint unless I have to. It doesn't seem as bad under heavy acceleration, but hard to tell (maybe just me).

 

[Bob V]

After a semi-long drive at speed get under the truck and see if any of the joints are worm/hot.