This is the second I have found this year. It was very corroded, so I built an electrolysis machine, used it sparingly, then soaked it for 24hrs in vinegar to remove the cement type crust. I would use this method to remove cement off my tools when I was a concrete lab rat for local concrete co. I only did this enough to at least read the date. It was found in the yard where I live. This is where I found the 1961 badge, and this one is dated 1953. I am working with DMV archives to see if I can find who these belong to. I would like to give them back.