LOL,,,dang it I wanted to know what did cause it so I wouldn't think about it anymore!!!!
here's a link to excellent correct mustang wiring diagrams...
http://www.hammar.dyndns.org/~djhamma/wiring.htm
suggestions:
move the harness to the top of the rad support (where it belongs)...
move the voltage regulator over next to the alt,,,you only need the idiot light (green/red?) wire going into the car....
wise to add a fusible link or slow-blow fuse to the main power feed (black/yellow),,,there is none now...