OMC Cobra upper gearcase water passage

[kpoly]

Over the winter some water got trapped in my OMC Cobra upper gearcase and popped out the plug on the port side, that is part of the water passageway. I don't believe any internal damage was caused but what is this part and does it have a name so I can order one? What is its purpose?

 

[Lou C]

https://www.crowleymarine.com/johnso...cfm?mdl=ITALGD

the earlier parts diagrams did not show these parts, but you can see here what's needed. a mistake that was made in these diagrams is that the image is flipped from left to right. So the plug is actually on the port side of the outdrive, not on the starboard as it appears in these diagrams. It is actually a screw and a retainer and some other parts....