As long as the bases have the proper offset of the locking lugs and the proper number/position of the contacts, the bases don’t care what voltage bulb is in place. The bulbs are only for lighting the gauge for night driving nothing else. The 6 volt wiring is plenty heavy enough to handle the much lighter 12 volts. Read the Stovebolt Tech Tip on 12 volt conversion to ease your mind about what your doing.
