Well, I'm no expert, and it's been a bunch of years since I've done one of the 6 volt to 12 volt conversions, but let's see what we can do to get you started, maybe someone else will chime in with better info.

First of all, buy a Runtz 12 volt to 6 volt converter from Speedway for each gauge to drop the voltage. As I understand it, gauges are NOT polarity sensitive, which means you can hook up the positive lead right to the old negative terminal an it will work fine. The only exception is the Ammeter, on it you have to reverse the + and - for it to read properly.

Like I said, I'm not 100 percent sure about the polarity sensitive thing, so maybe someone else can help.

Don