[50fordcoupeman]

I would say determine if your battery is 6v or 12v (if it has one in it) and that would shed a lot of light on your dilemma. Don't base your decision alone on what bulbs are being used because 6v bulbs (and other 6v stuff) can be made to work on 12v.
I am sure folks will add more to this. Let us know what you find. Good luck.