I have installed an oil and water temp. gauge for my 455 in a 74 Cutlass. I am now trying to figure out which wire to connect to get the bulbs to dim. I am guessing the headlight switch dimmer wire. But which is the dimmer wire. I am guessing the grey wire. Any thoughts.

 

You can splice into any dash wiring that dims. I like mine full bright all the time, as they are below the dash.

 

The wire is gray on a 66. You can splice in to any wire that goes to a panel light.

 

I just got done wiring my lights and gauges yesterday, the wire i used for my gauge lighting was gray and they all dim. 70 cutlass

 

I do remember it being the gray wire but that was 25 years ago.
Thanks.