TOPIC: Strange Merc 58A attachment. What does it do?

Bought a merc 58A with this item on the upper cowl. I have no idea what its for. It looks factory made. Any help would be appreciated. Thanks Frank...... I hope I can get the picture to upload.

It is the exceedingly rare Mercury Stern Light option. Only available for a few years.
You are missing the crystal, the pole and the guts which included a gravity "ball switch". I may be able to help you out as I have guts for 3 and am only using 2.
Let's talk trade...

here is the assembly minus the ball switch which is in the pole.

Thank you very much for the help. That is quite a neat piece. I would like to make it funtional. What would you like in trade? I have tons of Merc Mark 30 thru Mark 78 stuff. Frank.