Here's websites with pictures of the 3G installation...
See
http://www.geocities.com/smithmonte/Auto/3G_130A_Alternator_Upgrade.htm - all the tech data you could ever want to know
OR
http://www.mustangcentral.net/tech/alternator.html - excellent pictures of installation
Use these sites for information on the right way to do the wiring. Some people will tell you that you can skip the wiring upgrade, but it will catch up with you sooner or later. A fire in the wiring harness is ugly and expensive.
Under no circumstances connect the two 10 gauge black/white wires to the 3G alternator. If the fuse blows in the 4 gauge wire, the two 10 gauge wires will be overloaded to the point of catching fire and burning up the wiring harness.
The secondary power ground is between the back of the intake manifold and the driver's side firewall. It is often missing or loose. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges.
Any car that has a 3G alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects.
See
WWW.partsexpress.com for the fuse & fuse holder.
Fuse @ $3.90 each (need one)
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=071-952
Fuseholder @ $5.80 each (need one)
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=263-630
4 gauge black wire @ $1.25 a foot (use string to lay out routing & determine length)
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=100-196
4 gauge red wire @ $1.25 a foot (use string to lay out routing & determine length)
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=100-194
4 gauge ring crimp terminals (package of 5) $3.25.
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=095-584
Pre-fab 4 gauge cables with lugs already on the ends are available in most auto parts stores. Look for the starter switch to starter cables.