Try asking over at smith-wessonforum.com.
1950
No sn data published.
Your serial number indicates that your Smith and Wesson model 29 was made between 1977-1978.
1958
2015
Without a sn, there is no way to answer.
Made @ 1947.
No way to answer without a sn.
No sn data.
Made from 1955-1980. Based on the sn yours would be an early one. Call Smith and Wesson and they will assist you.
Made @ 1970.
1967