[AL in NY]

I use a TomTom in my CCPU on 6 volts and it works great. If your GPS plugs into a USB port(5 volts), it will work on 6 volts. They usually have a GPS cigarette lighter power supply which has a voltage regulator circuit in it to keep the output voltage to the GPS unit constant at 5 volts. You just need to wire a cigarette lighter with the negative for the case and the positive to the center contact. With the case wired to negative, you have to insulate it from the Model A's positive ground when you mount it.