Odd, that appears to be a .5 microfarad, 200v capacitor. Not sure why you'd have one of those connected to the ammeter. (Capacitors block DC voltage.)
If you're using the stock, 6 volt gauges, you will need resistors to reduce the voltage to 6 volts for the gas gauge. Randy Rundle, who is the Garage Foreman here, sells a Runtz voltage reducer which will do the trick. Don't recall the price off hand, but you can find a link to him on our Links page. You can also just go to Radio Shack and buy a proper resistor (but I don't know what values you'd need.)
