If you are hooking up the stock amp meter, wiring should look something like this (in a Scout the wires going to the amp meter are usually light blue). If you are hooking up a voltmeter, which basically just tells you if the alternator is working or not, then you go from a 12v source (preferably the "welded splice" junction) to ground. Note that if the 10 gauge wire going to the amp meter shorts someplace, you will be arc welding with whatever the output of your alternator is, usually about 35 amps, or the battery output which can be several hundred amps.