Those are Town and Country Horns. They were available in 1939 or earlier, for Chevy automobiles. They are listed in the 1946 Chevrolet Truck Data Book as an option for trucks. "For all model trucks. Matched electric two-toned horns." They were offered with a selector switch labeled "Town" or "Country".
The horns were made with two small dual and also with two large dual trumpets. They are a cool GM accessory IMO.
