In 1953 Chevrolet/GMC trucks adopted the more modern relay activated horn. To keep cost low, GM used the same seashell type horn that had been on Chevrolet cars since 1949. It displays the number “689” in its die cast metal. In the Chevrolet Master Parts Catalog, the number when ordering a replacement was 199687.
Though the 1953 truck used the existing car horn, GM created a special right angle bracket to attach it to the small extension on the iron intake manifold. This bracket has become very rare today. Most people incorrectly think the 1952 and older horn should attach to a 1953.
1952 and older horn position (above)
Just right on a 1953!