Well, the noise is back although I think its a little different than it was before. I can also feel a decent amount of vibration. Both of these things vary linearly with speed (the faster I go, the louder it is). I replaced the driveshaft center support bearing last night but that hasn't really had any effect on the noise or vibration that I'm experiencing.

While I had things apart, I checked the rotation of the three u-joints that I haven't changed and they all seem to spin freely although I suppose they could have axial play that I really would not be able to detect by doing this.

My next steps are to:
1)Check the alignment of the newly installed bearing again
2)change the remaining three u-joints (they're cheap and easy)
3)Have driveshaft checked for runout and imbalance
4)start looking at other components like rear diff and transfer case.

In other good news, I'll be doing my rear brakes soon also.