Put the new u-joint in last night. Took about 3 hours. I had a hard time getting the ends of the driveshaft assembly off the of their respective mating flanges, until I took a chisel/wedge and drove it into the only gap between the yoke and the flange, and then each end popped off right away. Then, I used the advice of the u-joint write up on the jeep section of 4x4wire (u-joint change) and got the first couple caps knocked out no problem... but then I had the u-joint still in the small end yoke and had no way to get it out. I should have knocked out the caps to get the small yoke off first, then I would have still had the driveshaft to aid in holding the assembly while the last two joints caps were knocked out. But, I got it all apart.

So, I started pounding in the first two caps of the new joint, but no matter what I did I could not get it to go together enough to get both c-clips on... I had about .040" more to go, and I could not get the caps on any farther. So, I took it all apart again, only to find that one of the needle bearings had become dislodged and was sitting in the bottom of the cap, resulting in the ~.040" gap that I couldn;t get rid of. Anyway, I packed a bunch more lube into the caps, and made extra sure to slide it all together while not letting the bearings move, and then it all worked fine.

End result is a much quieter and smoother truck at highway speeds. I can actually make out individual cars in my rear view mirrors on the freeway now, since the vibration is gone.

Thanks again for the tips guys.