1970 c20 brake input signal wire for trailer brake controller

[paulbrgr9999]

I am installing a trailer brake controller and wiring in my 1970 c20. Somewhere near the brake petal and steering column there is a wire I tap into so I can wire the controller. Does anyone know what wire that would be? Its color? Do I expose every wire under there until I find the one that sends the brake signal? Can I tap into the fuses to wire the controller?

I searched this forumn and did not find specific information regarding my truck. Can anyone help me out here?

thanks,

paul