Re: Trailler lights
As a suggestion, use Google Search - Images feature and enter "trailer lights" as a search string. Search through many different light pictures until you find the light picture that you need (to match other side). Drill down into the picture and get its Maker and/or Part number. With Maker and/or Part number (for example: 01645), do another Google search and use text string "01645". Then, scroll up/down to see the different companies who sell this specific light assembly. For example:
trailer light assembly - Google Search
If unable to find exact match of other side, simply find something that looks close and replace both sides. I had to perform this "replace both sides" when replacing the broken light assembly on my boat's trailer.
For another tip? Purchase / install LED lights (if possible). LEDs take water exposure much better than conventional light bulbs. Especially dipping hot bulbs into cold water - when unloading boat after long drive.
Hope this helps?