Well, I had one that was S/N 522XX which had a date stamp of 1966. If you look on the barrel just forward of the nut (might have to pull the barreled action out of the stock) there should be a stamp that has a letter and number inside a circle. The letter will indicate the year it was manufactured.

J = 1958
K = 1959
L = 1960
M = 1961
N = 1962
P = 1963
R = 1964
S = 1965
T = 1966
U = 1967
V = 1968
W = 1969

1969 was the last year the date code stamp was used.