[1894]

Does it have a serial # on it ? If so you can use X's for the last couple of numbers but include any letters If not I just ran across this with a quick google search ( so take with a grain of salt , but may be helpfull )

http://www.thehighroad.org/archive/index.php/t-149215.html

One of the posts there says this

Polishrifleman
July 29, 2005, 02:36 PM

Model 81 1937-40
Model 81E 1937-40
Model 81C 1940-70
Model 81DL 1940-1965
Model 81G 1960-65 May be marked Glenfield as well.

Straight out of the Blue Book, hopefully that will help.

 

[1894]

Your rear sight looks similar to the 2nd one down on this page :

http://books.google.com/books?id=a9...ge&q=Marlin extension rear peep sight&f=false

 

[1894]

And it seems that some were made with a clip ( detachable ) magazine , and most had a tube magazine. Hard to tell from your pics which style you have .