I changed from lights to guages. Wiring diagrams I bought show only wiring for idiot lights, not guages. Thanks in advance
David 828 684-0065 days

you will have to run 1 wire from the gauge to one of the hot terminals at the horn relay. the other wire must go to the battery junction block.
use 14 or 16 guage wire. you must splice in a short piece of 18 or 20 gauge fusible link in each wire near where it connects in the ngine compartment. this will prevent a short circuit from starting a fire (hopefully)
make sure you remove the old generator lamp wire from the dash connector-just cut it or tape it out of the way because if you don't, it may drain your battery

Start a fire??? HAHAHAHAHAHA, been there done that. What a nightmare. Yes, I had the smoke flying in my alley. Yanked the positive battery terminal off(suprised at how well new one are made-----VERY cheap) and the smoke cleared. Pushed the car back to the house by myself. I am amazed at how heavy a 68 chevelle is.
Just make sure you know what you are doing before wiring it up. And I hope you don't have to push your car like I did.

DDave,umm Im not tryin to deture You,but someone mentioned to me that runnin a Volt-meter is safer that an Ampmeter,,,I dont know exaclly why ,,but I am cntinplating the same thing on my 68 elk. I have to say I havent hooked up My ampmeter yet ,,,I had a fire in a 55 chevy PU once ..what a drag that was,,and I definately dont want the same thing to happen again!!!!! Sorry I cant be of more help... good luck