subtract the first 2 digits of the serial number from 100, that is the year of mfg. they were mfg. from 1973 til 1983
your glenfield was made in 1968.
1980.
1978
1967
1978
1967
With the serial number that you have provided,your Glenfield model 30A was made in the year 1977.
35yrs
1972.
Your serial number indicates that your Glenfield model 20 bolt action was made in the year 1980.
Your serial number indicates that your Marlin model 60 was made in the year 1971.
write to marlin with any and all writngs/markings on reciever/barrel and serial numbers