FYI. The non-locking gas cap from various VW Golf/Rabbit models, p/n
172201551B, fits my '81 Vanagon just fine. I suspect it will work with
later years, too. So, if you misplace your gas cap, or want a
non-locking one, that's something to look for. They're still seem to be
available from various places, unlike the original non-locking Vanagon
one.

I discovered this while picking up some bargains at rockauto.com. They
had a Stant 11808 "fuel pump cap" listed on "wholesaler closeout" for
$3.41. I figured that might be a weird description for a gas cap, and I
was right. The Stant cap was actually the VW OEM one mentioned above,
in Stant packaging. Stant probably made them for VW (marked Made in the
USA!), because the Westmoreland plant was making Rabbits at the time.

It looks like they still have at least 1, if you do a part number
search for 11808. Down to $3.39 now.