If you can't figure it out poking around on the internet, take the bulb out and take it to your local auto parts store. The guy at the counter should be able to tell you right away what kind of light it is. Take a look at the package and note the bulb type and you're GTG. Most likely it's a 921 (flat socket) or a Ba15 bayonet (round socket).
Pay special attention to the temperature of the lights. I just put some in my unit that are labeled "white" and they still look blue to me. Especially if you are not replacing all the lamps at one time and you have LEDs in the same room as incandescent, then they look really blue (even if they're "white").
I just ordered some more that are labeled "Warm White" or 3000K-3500K IIRC. I'm hoping they will be more acceptable to DW. The blueish tint of the "cool white" or the "white" bulbs just doesn't look very inviting.
Once you find out which bulb you need, only order one or two until you are sure you have the right color. Amazon is a pretty good resource for some cheap bulbs. Once you find out what you really like, then you can drop a few more coins on something that will last or has a warranty.
Here is another good reference with examples of what the light will look like.
2014 Jay Flight 28 BHBE
2015 RAM 2500 6.4L HEMI, Tradesman 4x4, 3.73
Blue Ox SwayPro (BXW 1503)
Upgraded from an REI internal frame backpack and a Eureka 1/2 dome tent!