i have a 73 mach 1 and i'm having a little electrical problem. when i drive it during the day it does fine, but at night when i have the lights on it kills the battery. i changed out the battery, alternator, regulator, checked for electrical leaks but i still cant get to the bottom of it. i know its a small fix but i dont know what it is or where to start. so if i could get someone to give me some pointers or lead me in the right direction i would greatly appreciate it. i have tested the battery and the alternator. i have even switched them out but it still does not want to work right.