Marlin used a letter code starting with c in 1946 and changed one letter a year skipping the letters I O and Q thru 1963 then used y z for 1964 and then started AA ab etc
No way of knowing without you providing a serial number to find the year of production of your Marlin model 39A.
With the serial number that you have supplied,your Marlin model 1894 was made by Marlin in the year 1895.
For Marlin manufacture dates head to the site linked below. (see related link at the bottom)
With the serial number provided,your Marlin .22cal rifle was made by Marlin in the year 1985.
your marlin model 1897 was made by marlin in 1903.
Your Marlin model 30as was made in the year 1988.
What year was Marlin 39A Mountie S/n 19968 made
Your Marlin was made in the year 1999.
You will have to contact Marlin to find out.
your marlin model 336A was made by marlin in 1950.
Your Marlin model 780 was made in the year 1977 with the serial number that you have provided.
Your Marlin rifle,not shotgun was made in the year 1972.