Instrument Voltage Regulator for 65 Dart

^^You guys are missing the point^^ I forget it was either 1 1/2V or 3V (two cells) that you connect direct to a gauge and it gives you a partial reading. If you have a gauge you suspect is "OK" then all 3 should read pretty close to wherever they come "up scale." 5V will peg the meter.

I can not find that thread.