Obviously its amps versus volts, but what I mean is installation. I was under the assumption that I could just stick my aftermarket volt meter into the wiring where the ammeter used to be,( Big Gauge red on one side, big gauge black on the other) but I am getting conflicting opinions. The instructions withe SW gauges ( poor instructions at best) says negative post of voltmeter is supposed to be grounded ( ???). I thought in the stock harness I could just attach the red to positive gauge post and black to negative post of gauge.Thanks , Neal