fwiw  the Stant 11810 fits pretty well
and is about $5 from your FLAPS
(checker auto parts here in AZ)

beats the heck out of the $45 that
VW wanted (if they can get the proper
one ordered)

Can also get one from busdepot and
have it keyed (per the info on the list)
as well.

There was nothing wrong with my OEM cap..
maybe the gasket a *little* worn.  They just
flunked me based on that, since it didnt fit
onto their tester thingamabob that well.

hope this helps

  -tim

90 syncro westy
mesa, az