I believe that the small sparkplugs were used in 1935. I do have a reproduction 1936 aluminum head, polished, that I would sell. Including the polishing, I have $1400 invested. I would sell the head for half that. This head was standard from 1936-1938. Please speak to someone knowledgable about these aluminum heads before you consider buying mine. I could deliver this head to Hershey, if anyone else is interested. Tony