Proven Force Clutch and U-Joint of Minneapolis has been very helpful and
successful at replacing Syncro driveshaft u-joints.  For around $100 plus
UPS shipping they will replace both (always do both) of the u-joints and
spin balance the shaft.

You can call them at (800) 444-0755.  Be sure that you contact Todd as he is
their expert on this arcane issue.  They have worked on a few dozen Syncro
driveshafts (including mine) over the past two years and seem to have pretty
good success.

Please realize that there are multiple other causes of driveshaft vibration
beyond the u-joints, although they are a classic maintenance issue.  In any
case, this route is much preferable to the $700 usually charged by VW
dealers for a rebuilt driveshaft. Please check the Bentley manual or the
List Archives for further discussion, including tips on shaft removal.

BTW, no damage will be done by driving a Syncro indefinitely without the
driveshaft.  You simply will have a slightly taller and heavier 2wd.

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