Missing orange cover on marker light; Water leakage concerns

I just went through this exact thing on my trailer. Take a wet towel can clean the dirt out if the light base. I can see a number embossed in the attached picture but I can't quite make it out. If there is a manufacturer name try searching for that too.
But take that number and type it into Amazon and see if it gets any hits. Also try a google search of the number + marker light and see if you get any hits.

Mine was from 2005 so it probably wouldn't work for you but here it is just in case.
Amazon