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If it was manufactured between 1949 and 1970 there should be a small circle with a number and letter stamped inside of it, between the trigger and the hinge pin. The letter reflects the year of manufacture. *The date code may also be on the flats of the receiver where the barrels rest on the receiver.
Stevens Date Codes
A 1949
B 1950
C 1951
D 1952
E 1953
F 1954
G 1955
H 1956
I 1957
J 1958
K 1959
L 1960
M 1961
N 1962
P 1963
R 1964
S 1965
T 1966
U 1967
V 1968
W 1969
X 1970
After the Gun Control Act of 1968 took effect, serial numbers were required on the reciever of long guns. No date code, no serial number; likely pre 1949.
Here's a link to parts,
Firearm Parts and Accessories | Numrich Gun Parts Corp. | e-GunParts.com 
