The Model 24-S (side lever) was made from 1964 to 1971, but since yours has no SN, it would have been made prior to the passage of the Gun Control Act of 1968 (GCA-68).
Savage marked all their guns with a year date code stamped into the barrel bottom or receiver - a letter within a circle, starting with "A" in 1949, and ending with "X" in 1970.
R= 1964
S= 1965
T= 1966
U= 1967
V= 1968
.