[Brian Belcher]

This is for anyone with the answer but I figure Steve will have the answer.
The adaptor that buckles on the vacuum hose for draining the holding tank. ANyone have a clue on common size or where to get it ?
Sorry for the pun BUTT, using the shop vac sucks.

[Hudson River Steve]

Believe they are called pump out nozzles. You talking about these:
Pumpout Accessories : Edson Marine Store

[Brian Belcher]

Yessir. That would be them. Do you happen to know if the quick couple side is a universal 1 1/2"? I'll have to measure the thread size on the boat, 1 1/2 or 1 1/4" thread.
I don't want to have to go through that hell again !

[Hudson River Steve]

Brian,
The quick clamp (camlock) side is standard at 1½". I am not sure what the thread size is on the boat fitting. I have never used the threaded connection. I always use the universal rubber nozzle.

[ShabahZ280]

Same here, always used the rubber nozzle for the pump outs at the fuel dock, never messed with a threaded hookup. I assumed the threading was just there for the cap.