The strange thing though is that just as the vibration starts at 78mph (indicated - the tires are taller than stock) it also stops right at 82mph - above that it is smooth.

The tire wear is also very uniform. I've tightened the steering box and all the rest of the front end has no slop that I can find.

In my testing today I'm questioning my thoughts on the rotor. If I apply the brake (just a tiny bit) and it was a warped rotor it seems the vibration would change (for better or worse) but it does not change. I can also feel the vibration come and go more in the transfer case lever than I can in the steering wheel.

So I'm back to wondering about the balance of the drive shaft and/or the possiblility of the front U Joints being bad. The drive shaft was put back together the same way it came apart but the U joints are different - the new ones have the zerks at the ends of the caps where the old ones had the zerks at the base of the joint.

Could the placement of the zerks be enough to make the driveshaft out of balance?