amp gage should be red going in [positive] black going out[negitive]. a volt gage would be better in my opinion. the gas gage should have a power [ + ] and a signal feed [ from the tank sender]. it could also have a ground terminal, but i haven't looked at a 33 gage panel in a long time. don't forget the original gas gage was a 6 volt item, so if you hook it directly to 12v without a stepdown resistor[ or whatever it is called] it will fry . the amp gage will work as is, provided it can handle the output of your alternator. if it is only a 30 amp or so, i wouldn't try it. glad to hear you are having sucess with the install.