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
35yrs
1972.
Your serial number indicates that your Glenfield model 20 bolt action was made in the year 1980.
To determine the age of a Glenfield Model 35 rifle with a serial number starting with "AC," you can refer to the serial number charts specific to Glenfield or Marlin firearms, as Glenfield was a subsidiary of Marlin. Generally, Glenfield rifles manufactured in the 1970s often have serial numbers that begin with "A," and the "C" may indicate a production year around 1972 to 1973. For the most accurate dating, consult resources or forums specializing in vintage firearms or reach out to Marlin's customer service.
write to marlin with any and all writngs/markings on reciever/barrel and serial numbers
Your serial number indicates that your Marlin model 60 was made in the year 1971.