First: THanks for that link, Mine is not like that one (It's a block) but I saw one of those the other day and want one.
Next. I use an adapter with a "Yummy Sewer Donut" this is a fairly hard foam ring that goes around the straight or stepped (non threaded) adapter. it will also fit on a threaded adapter.. ANd I use the Water block (or PIG) on top of it.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times