I'm looking at a 66 wiring diagram and if I'm reading it right the tail light wiring is black on one wire and orange/blue on the other wire on the passenger side and on the drivers side it looks like black and green/orange. Don't know if the colors are the same as a 65 but I kind of expect they would be. Wire size isn't listed. CJ Pony has wiring diagram manuals for $4.95. I havn't started rewiring yet but this will come in handy when I do. Hope this helps.
Mike
Mike