Courtesy light bulb and dome light questions

[65chevysub]

I have an 84 GMC Sierra 2500, that didn't come with a dome light, only an under dash courtesy light, ( or cigarette lighter,) but was wondering if someone could tell me what bulb number would go in the under dash courtesy light? I have power so it should work. Also, if anyone else here has a truck without a dome light, what did you put in to light up the cab? I was thinking of an RV style porch light or something similar. Can you post pics, please?
Thanks