My 11 year old son and I just bought a Marlin 81 DL from a guy on ODT (super dude. Thanks). Anyway.......we are trying to identify the year of the gun. There are no serial #'s that we could find (therefore pre 1968?). It is a bolt action with a tube feed. Guard around trigger appears to be not original.? Looking on You Tube there is a guy that has one that looks almost identical and he said that through research he figures it is between a 1937-1941(2). Is there anything that we could do to find out when this gun was made? The condition of the stock is very well worn (not banged up and hacked, just has a beautiful "old" patina----great character in the wood). Any help to our novice gun family would be appreciated.