The bracket for the horns is riveted to the horn from the factory, when you find the correct horn, you'll have the bracket. They bolt to the core support with one bolt going down into the top and one bolt going into the vertical part of the core support top angle iron on the engine side...there are louvers cut into the core support side panels to let the sound out.
The correct horns are the "sea shell" type with half of a sphere cover.
Left Low stamped 759
Right Hi stamped 760
Mike B
