Get one from any VW speed shop (the air or H20 cooled sort) or
mail catalog.  About $5 from them.

Sears may just have it if you have a great Sears.

An M10 ? bolt (I'm not sure I think 10 will have a 17mm head)
with a couple of nuts double nutted is another option in a pinch.

BUT make sure you pull the fills BEFORE the drains, particularly
if you are using a home made "bolt" wrench.  And on the syncro
I recall the fill being a real PITA without a proper wrench (the $5
job has a 3/8" socket drive) due to clearance issues.

John
jander14@wvu.edu