need help with a ford(sorry)

[bigstew]

my driver right now is a 81 bronco, but just until i get my sub going. but i need some advice on the wiring. i have put a new alternator, new battery, and a new voltage regulater on it. the problem is the alternator will not charge the battery. i just got the alternator tested and it is putting out 15 volts. when it is in the bronco it is only putting out 11.50 volts. what else could be the problem? im real close to fixing it with a rag in the gas tank and setting the rag on fire.thanks