Evan, Thanks for the confirmation.
Well, those VW parts #1H0-837-227 are not so available as I thought. I ended up ordering a couple off eBay... from Latvia... for $12ea (crazy).
(note: Be careful on eBay. Some vendors list items with reasonable or low prices, then super crazy shipping. I've seen similar behavior on Amazon. One listing had these for $8 ea.... with $190 shipping!!)
I still have a question about what's filling the 2 slots.
Did I remove old o-rings? Or, is it dried hard gunk? I can't tell. I have not seen any references in any threads about them.
If they are actual o-rings, what was their purpose? I'm not sure if I should try to find substitutes. Probably just leave them open.