Otto,
The info I gave you abut the wire existing by the steering sector is for a 46. It apparently was moved for the 1950 truck. That is your horn wire. See if you have continuity between the horn wire in the engine compartment and the brass surface of the steering wheel bearing. If so you are good to go! The other wire for the horn should be "hot" 6V to complete the circuit.
The insulation on the wires looks to be in good condition. Very rare in trucks of this period.
Harold
