the years before GM wised up and added a relay to the horn circuit, about 54? then the horn only had 1 connection, power from the relay and the horn mount is its ground
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics