Your Smith and Wesson model 15-3 was made from 1967-1976.I am afraid that's the best I can do at this time.
@ 1969
1980
@1977
Impossible to answer without the serial number.
1966-67
Impossible to answer without the serial number. You will have to call S&W
@1975
Need a detailed description
@ 1960
1969
Either late 1800s or early 1900s
You will have to call S&W