I have indicated in the past the great work done by Proven Force Clutch and
U-Joint of Minneapolis, MN.  They will install two new u-joints of the
proper size (yes, they are from a tractor power take-off) and dynamically
balance the shaft for a bit over $100, plus UPS shipping both ways.  They
use a specific procedure to fit the u-joint properly (something about
cross-trunion spacing...).

They have done this on my 86 Syncro and about a dozen others with fine
results.  Please contact Todd there at (800) 444-0755 and let him know you
heard about him from the Vanagon List.

Much more detail is available in the Archives.

Good luck.

Budd Premack
86 Syncro, 73 Super
Minneapolis, MN (Land of Sky Blue Waters)