I don't know about your wire colors, but on a 10 or 12SI with the plug terminals ("three wire" alternator), one wire is your "sense" and the other is to dash light like Ray said. The sense wire can simply go to the BATT+ output (which is basically what is going on in a One Wire alternator), or ideally, it would run over and remotely tie into your main feed bus, like at a +junction block, or on your starter. American Autowire's kit has you just jumper the sense to the BATT output. Mad Electrical recommends you run the sense to your main feed bus.
see
http://www.madelectrical.com/electri...hreewire.shtml