Ok I have a 2000 2wd. SR5 3.4 lifted 3 inches 33's I bought it for $5K but instantly put $3k into it. Tie-rods, Ball joints Uppers/lowers, steering rack, all fluids change, Timing belt, water pump, Shocks, etc.....one thing I didnt change was the U-Joints. a few months ago check engine light came on and it was a 420 code for catalytic Converter. I reset light and a few weeks later a loud vibration hit at 60 mph. many people told me U-joints. so I changed the U-joints and catalytic converter. Problem didnt go away. I have no idea what else it could be. Question tho: There is some sort or resonator before the Cat. Could that be plugged? Could it be that I need to replace the entire Drive shaft? some people are telling me that I should have done that instead of just the Ujoints. The Ujoints werent that bad in the front, but the back ones were a bit worn. The truck has 182K on it.

The Noise is a Zippy Noise, almost like Im riding on a shoulder with cuts on the road......Oh I just got an alignment today too and it was very bad.....but the problem is till there.....could the resonator thing be shaking cause its plugged? could the drive shaft be shot where it goes into trans? Could it be the Rear END?

I'm betting driveshaft, only because I had this happen at about 130k. You said you replaced the U joints, but not the shaft. If the end of the shaft was damaged, then putting new U joints on wouldn't solve the problem. I'm my case I replaced both the joints and the shaft and everything was smooth again.