Take a look at the pic below. This shows how to wire a 3G. If there is anything on there you don't understand or have questions about just aks. I don't know your wiring back ground so this is a good place to start.

wsinsle wrote:

Take a look at the pic below. This shows how to wire a 3G. If there is anything on there you don't understand or have questions about just aks. I don't know your wiring back ground so this is a good place to start.

This is very helpful and at some point I'm going to do it.  One question:  why is the original alternator fan from the pulley not used on the 3G - does it have it's own internal fan?
 

Also keep in mind if you are using thge original alternator and bracket. There are 2 3G alternators with mounting holes 180 deg apart. A large case and a small case. If you use a small case it will work with the original mounting bracket. You just may have to adjust spacers. I think mine came from a 95 mustang 5.0 and it was a small case.

ultrastang wrote:

Among different case sizes and varying mounting configurations, there are also TWO Primary Amperage Ratings For The 3G alternator. One is rated for 95 amps and the other is rated for 130 amps.

The 95 amp version is a 4 hole case and the 130 amp alternator is a 2 hole case. This can be determined by looking at the front of the case. Radiating out from the center of the case will be 3 pairs of ribs, every 120-degrees apart. Between each pair of ribs will be some small round holes. 4 holes between each pair of ribs denotes a 95 amp 3G alternator. 2 holes will be a 130 amp alternator.

http://alternatorparts.com/ford-type-3g-4g-6g-series-high-output-alternators.html


4 hole case 95 amp 3G on left, 2 hole case 130 amp 3G on right.

http://publicphotos.ishouldntwonder.com/albums/F250/restoration/forum/2014_02_25/3Galternator_small_large.gif


http://www.supermotors.org/getfile.php?id=145797&toggle=fullsize&f=.jpg

The vehicle list below will be donor sources for the 130 amp 3G alternator, charge lead/pigtail wiring and the 175 amp Mega fuse.

(1994-95) Ford Mustang 5.0L
(1994-00) Ford Mustang 3.8L 
(1994-97) Ford Thunderbird, Mercury Cougar 3.8L 
(1990-95) Ford Taurus, Mercury Sable 3.8L
(1993-99) Ford Taurus, Mercury Sable 3.0L
(1995-98) Ford Windstar 3.8L & 3.0L
(1991-94) Lincoln Continental 3.8L 
(1992-97) Ford F Series Pickup
(1992-96) Ford E Series Van

Can you recommend a resource for deciding on the amperage necessary for a 65 Mustang, assuming modern A/C, reasonable stero (e.g., no amps in the trunk), no power windows, no electric steering, upgraded headlights with extra driving lights, usual interior lights and gauges, etc.?