how to wire up a voltmeter to a 3g alt.

ok i got a 3g alt. it's not the 130 amp version but it's a 3g. the wire that is how when the key is on goes to my aftermarket voltmeter right. there are 3 prongs on the gauge. one has a G next to it for ground i am guessing, one has S on it. maybe for stator but i don't know and the other has I for ignition maybe. but the directions suck. it only shows 2 prongs on the picture and says one is switched power or ignition and one is ground. what is the 3rd prong for that has S next to it. do i even need it to be hooked up. i see in a 3g wiring diagram that a wire comes from a switched power source then to the charge light and off to the regulator on the alt. with the letter "I" on it. is that where i hook the 3rd prong on the voltmeter to instead of the charge light. here is my diagram on the 3g alternator wiring.

http://images.google.com/imgres?img...ev=/images?q=3g+alternator&svnum=10&hl=en&lr=

ok thanks for the quick reply. that is all i needed to know

well i tried that and the needle just pegs out. i am going to put a wire from the stator of the alt. to the S prong on the gauge and see if that helps. right now i have switched power to the I on the gauge and ground to the G on the gauge. i tried putting switched power to the S prong and it just blows my #18 fuse