So I thought an amber marker light went here but looking at my buddy's new to him trailer and boat  he has a  plug here that his trailer wiring hooks up to .
It's an og from 1980 comp trailer and I am trying to bring her back to where she was new.
Any thoughts of what goes there and where I can get it ?
It's an 1.5" hole

You can get them at hanks hardware or tractor supply or some auto parts stores

Sent from my SM-G930P using SoCal Jet Boats mobile app

thanks   I think that's what I need