I made a big mistake long ago - I took my truck apart without taking pictures or making diagrams. (New folks - remember to take LOTS of pictures so when you try to put it back together, you have something to go by.) Now I am putting things back together and I cannot see where to mount the horn on my '58 3200. Any help is appreciated!
55-59 Chevy Truck Assembly Manual shows the single horn's two studs attached to a bracket assembly which is bolted to the top of the radiator upper tie bar using a single bolt and an external star lock washer. In the drawing it appears to be about two horn diameters in from the driver's side inner fender panel. If your truck were a 3124 (Cameo, not made in '58) you'd have a second horn mounted the same way on the other end of the same bar.
Hey, 55-59 if you stand in front of your truck the horn goes on the right side of the radiator.You use the top bolt of the radiator on 58-59 and 55-6-7 use the top bolt and a bolt from the hood latch pannel. Cliff