Ford used 6 volt gauges from 1930-s to 1955. In 1956 all gauges were 12 volt. In 1957, and up to the 90's, Ford gauges were all 6 volt again. They used a (1) voltage regulator for all the gauges. You can see on every instrument cluster a little electrical thing-a-a-ma-jig, about 1 1/2 x 3/4 inches in size - this is the voltage regulator. Sorry to report this, but thats what Ford did.