I have a 32 dodge sedan positive 6 volt system. Recently swamping out all the gauges. So far the oil, amp and temp all working properly. The new gauges are wired for 12 Volt. I am not sure what I have to do about the fuel gauge. Can I keep the original sender unit or must it be replaced. I also installed a 12 volt converter just in case I decide to add radio etc. if my new fuel gauge will not work with the existing sender can I then wire the gauge to the new 12 volt converter. Thank you for any info you can provide.