Dedduc,
From your pictures and description that / those would be Model 37s or "pre" Model 37s. the 5 digit SN would be ca. 1953, and the 6 digit number between 1957 and 1962. If there is a letter J prefix to those numbers the first would be between 1969 or 1970, and the second from 1973 or 1974. The rubber grips are after-market, not original to the gun. Any letters associated with the butt number are part of the SN. These dates are from the "Standard Catalog of Smith & Wesson", 3rd edition.