Craig, I'm away from my trailer but IIRC all of the interior lights take a T10 Wedge Base LED bulb, which replaces the OEM bulb types 912 or 921 wedge base bulb in an RV.
I would pull a bulb in your trailer if I were you and double check just to make sure.
As for who to buy from, many buy Chinese bulbs via EBay. I'd list the sellers that I had bought from a couple of years ago but they're gone.
The Ebay bulbs are inexpensive but can be fragile. Order a bunch and try them out. This is also a good way to find if you like "warm white" or "bright white" and what level of brightness you like. Some of these LED bulbs can be too bright for certain areas in our trailer. It's personal and you will find what works best for you.
The better LEDs can be found online at specialty shops, often auto lighting specialists, although quite a few RV places are selling them now, too. Superbrightleds.com is a well known site to look at.
Happy New Years to you, too!
DW, 3 Kids and our Goldens
2012 Shamrock 233S
2008 Toyota Sequoia 5.7L 4WD