That's what I figured, but never hurts to ask. As far as wiring goes, there is three wires on the 3g. One white/blue that goes in a little pico connector on the side of the alternator, a yellow wire that goes onto the positive terminal on the rear of the alternator (this is also where you run the battery cable from then to the mega fuse or straight to the solenoid if you wish) and the green/red wire that goes to the green/red wire on your truck. I wish I was near my truck so then I could take pictures and show ya. Look at this pic, this is what you want the wiring to look like http://img.photobucket.com/albums/v4...wiring-1-1.gif The wiring on the alternator should look something like this http://www.supermotors.net/getfile/4...ess.jpg%20alt= out of the truck, of course.
This is an excellent picture for reference, even though it says for a '65 Mustang our trucks will work with this too. I know it shows the yellow wire running to the solenoid, what I've seen most people do is run it to the B terminal on the alt.

 

Because it came from a stock 97' with a 3g alternator and there are no splices in the wiring. With a 2g harness there would be a splice or two.

 

From the front (2G on left, 3G on right) http://i673.photobucket.com/albums/v...Picture068.jpg
From the rear http://broncozone.com/uploads/monthl...1232238578.jpg

I'm pretty sure that your year of truck should have one, but seeing as I have never seen a '97 from this gen I couldn't tell ya.

 

Sorry Guitar I asked it the wrong way lol I was wondering how to tell the difference so I can look and see if the p.o. upgraded the alt. on my truck.

 

You would know by the alternator. The 3g will be internally regulated and the 2g will have a metal fan on the outside front of the alternator.

 

Thanks for the explanation guys just got home and popped the hood and it has a 3g

 

This what I ordered.
http://www.latemodelrestoration.com/item/SVE-17046KB/1986-1993-Mustang-Alternator-130-Amp-50-Upgrade

http://www.latemodelrestoration.com/item/PA-9902/Mustang-3g-alternator-Premium-4-Gauge-Power-Wire-Kit-W-Noise-Suppression

Only thing u have to do is reclock the alt.