This question cannot be answered without you providing the serial number to you Glenfield model 60 .22cal semi-auto rifle.
that would be a 1974 model
1978.
1974, made in Connecticut.
Your serial number indicates that your Marlin model 60 was made in the year 1971.
your glenfield was made in 1968.
Your serial number indicates that your Glenfield model 60 was made in the year 1974.
1971
1975.
1975.
1970
1968
1968