You'll start with this. The horn wire is connected to the mast jacket bushing which is at the top of the steering column. It's connected inside the column (mast jacket), runs down the inside of the column and exits in the engine compartment through a hole on the bottom of the column. It then connects as shown in this diagram. It is the ground for the horn. Pushing the horn button completes the ground, closing the circuit, allowing the horn to honk. I can't help with the cab pics since my '38 is a car. Good luck.

Last edited by Tiny; 10/30/2010 9:19 PM.
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Name your dog Naked so you can walk Naked in the park.