I finally found the super rare 1939 Town & country horn switch, that allows to choose between "City" and "Country" horns.
First I installed the switch, but it was working in one position only. I removed the switch, opened it and cleaned the contacts. Then it was working properly in both positions, but when I installed it at the dash, the horns was blowing all the time when I turned on the ignition, even when I not pushed the horn button. I found it was because the switch housing get contact with ground and making a short circuit. It has to be isolated in any way. My questions:
1. Is it an internal error inside the switch that make the housing reacting with ground?
2. Or do I in all circumstances need to isolate between the dash metal and the switch housing? The strange thing is that I didn't have this problem during my first installation.

My thinking is that somehow when you took the switch apart an insulator was either left out or damaged. The switch parts must be isolated (insulated) from the case.

Thank you Chipper.
I opened it again and found that the small bushing around the switch shaft is teared and worn. No I am spraying it with CRC urethane paint, I seems that it will give a good isolation.

A reasonably thick coating of urethane should provide the insulation required.