One other question: is it normal that a good half-cup of gear oil runs out of the ball joint on removal?
Where do I go from here?
Karl
Yes, that is normal.
After a u-joint repair, on a enclosed torque tube drive line.
The tranny will funnel gear lube into the u-joint ball housing.
But then you should top off tranny again.
It will eventually level it self out.
The manual states to remove speedo gear and pour some gear lube into the hole.
If the rear torque tube oil seal is leaking, the tranny gear lube will keep running down the torque tube into the rear end.
As far as the vibration, you should check to see if the torque tube bushings are worn.
Below are some side views of the torque tube bushings and rear oil seal.
With Okie bushing and without.
Depending on the year of your truck, some bushings had a dowel to hold the bushings in place.
Chevrolet 1/2 ton 1937-Early 1950 Torque Tube Chevrolet 1/2 ton 1937-Early 1950 Torque Tube w/Okie Bushing Chevrolet 1/2 ton Late 1950-1954 Torque Tube Chevrolet 1/2 ton Late 1950-1954 Torque Tube w/Okie Bushing 
