Wacked Out Gauges

You should have a mechanical voltage limiter inside the 3 post fuel gauge. The capacitor attached there prevents a pop noise in radio speaker. A failing limiter will send too much power to the gauges and can damage them. Sometimes the limiter completely shorts out. Then the copper trace on the circuit board that carries 12 volts to that limiter will burn open like a fusible link which saves the gauges. Replacing the limiter with solid state regulator is the fix.