There was a 3 wire factory unit available. It used the tuna can light housings and not your park and stop lights. To use it with your park and stop lights you need to replace the 3 wire switch in the housing with a repop switch. If you intend to use the separate light housings for your signals you need to run new wires to them and terminate the wires in your new harness.

"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.