I had the chance today to look at an original Simplex speedometer. Stewart Warner made and looks identical to a Stewart Warner bicycle speedo I had. But! I noticed it was heavier than the bicycle speedo. Looking closely at the patina which looked green I could see a light color which looked like brass. After going outside where these old eyes could see better. This appears to brass with old oxidation, the green color. There is no rust on this anywhere except for the steel nut that holds the shaft. A magnet does stick to the housing. Whats up! I thought they were all steel. Could some of these have been made of brass or something else. I wouldn't have thought so, too expensive. Maybe something special I don't know. But it doesn't appear to be plain stamped steel. Any ideas?