If you are putting your battery in the trunk, Running a Killer Stereo or using an aftermarket SI alternator putting out more that 100 amps use at least a number 8 AWG wire between the Alternator and the Battery.

The above drawing shows the proper wiring of the Delco 10 SI Three Wire Alternator. One of the things that confuses most people is there is little difference in using this alternator or the One Wire replacement alternator.
If you are going to use a dash indicator light you might as well just keep this alternator.
If you are going to upgrade to a one wire because you want a chrome case then just install the new One Wire alternator and connect it up the same as your existing Three Wire alternator. If you look at the schematics below you will see that the One Wire will operate just fine wired the same as the Three Wire.
If you are installing a Three Wire alternator in a vehicle that is not properly wired for it you will either need a dash indicator light or you have to install a 10 ohm 10 watt resistor between the number 1 terminal on the alternator and an ignition source to properly excite the alternator.

Most Automotive Electrical Problems are GROUNDING Problems.  If you're having a problem with something and find there is power to it double-check your grounds (including the battery cables).

Need any help with your wiring problems just e-mail me. Any and all comments are welcome. If you feel something should be added please let me know. 
Al@AutoReWire.com