S&Ws does not provide a "manufacture" date. They can give you the date that it shipped. Your question is impossible to answer without the serial number. You will have to call S&W.
Call S&W
You will have to call S&W to find out.
You will have to call S&W
You will have to call S&W
The prefix letter shows the year of manufacture. 1956 is letter S
You will have to call S&W
4 years
about 1970
Call S&W and they will tell you.
@ 1976
@1977