1974 Determining the year after 1972 is the first 2 numbers of the serial number from 100. ie: 100 - 26 = 74 therefore year of manufacture is 1974
1974 regards russ
No sn data published.
Your Glenfield Model 25 is actually a Marlin Model 80 with sling swivels. According to leverguns.com Forums all of the Glenfield rifles were numbered right along with the Marlines. According to http://armscollectors.com/sn/marlinlookup.php your rifle was manufactured in 1973.
Brophy's book on Marlin History has sn information.
1997
No published sn data. The History of Marlin by Brophy might help.
http://armscollectors.com/sn/marlinlookup.php
Based off of the sn you posted 1966. http://armscollectors.com/sn/marlinlookup.php
Made since 1960. Unaware of any published sn data.
armscollectors.com/sn/marlinlookup.phphttp://www.savage99.com/marlin336_dates.htm
Your Glenfield was made in the year 1974.
Take 2000 the first 2 digits of the SN. 1986.