I had the same problem with our Salem 31kqbts! I looked on etrailer.com and sent them a picture and they did not have it. We even went to a local dealership that only sold Salem Travel Trailers and they stated they did not have it. How can salem make something that is so hard to find! Any help would be appreciated. Unfortunately there Is no part number on the actual bulb. I've looked in the online manuals and everywhere I could possibly think online.