I am in process of switching my 1947 ford from 6 volt to 12 volt and I searched the forum for ways to do the switch. I am really wanting to use the stock gauges. Do I have to reduce all the gauges or just some of them? It has a temp, oil pressure, fuel and amp gauges. The other thing I noticed on other threads is using the napa part number ECH IR-1 or the one Mart sells. What I am wondering is how to get one from Mart? Also will the napa one run all the gauges?