Think my horn is toast. What horn(s) were used on these trucks?

[derotoreut]

I think my horn is shot on my '69 C20. It sounded horrible then stopped working. I removed the horn and bench tested it with my battery charger and it beeped once and that was it. Does nothing. I don't have my steering wheel installed, but when I complete the circuit by touching the horn wire to the column I can hear the relay clicking. So I plugged a 12V test light into the horn wire in the engine compartment and it gets power when I touch the horn wire to the column. Does this make sense that it would be the horn?

What horn or horns were installed on these trucks? Were they a single horn or double horn set up? I only had one horn and one wire. The horn appeared to be an aftermarket horn. Where can I get a replacement horn set up if this is indeed the problem?

Not sure if this is the right location for posting this thread.