battery going dead after gauge install

You should have just hooked up the lights for the gauges to the headlight switch.. or you could hook them up to the dimmer switch so you can dim them if you wanted to.. And the power source from a key on 12 volts.. mine is hooked up to the power wire of the wiper motor
 
89MustangGX said:
The fuse he used goes through the dimmer switch, it's a better solution IMO.
i agree. that is a good source.
i think 18 is also dead with the key off. you could do the draw/short test with those two fuses. i doubt you did something to drain you battery (as long as the gauges dont stay on 24-7). might be coincidence.