WLA crankcase fitting

Can some-one tell me the standard part number or size of the fitting that screws into the back of the RHS crankcase.
The fitting that connects to the tube going up to the oil tank vent.
Can't seem to find it listed anywhere from any drawings.
Thanks in advance.

25235-36 crankcase oil tank vent nipple, '36 up W, WL, G, etc. It is listed with the oil lines.
Robbie