Windy, breaking it down, it's a Model 81, the DL could mean deluxe, but i will have to check further for sure. 22 rimfire and shoots shorts, longs and long rifle cartridges.I just joined up and 'aka' said maybe you guys can help me identify my Dad's Marlin. I'm so sorry but all I have is lousy cell phone pictures that probably won't help you at all but I will post them anyway.
This is what is printed on the Marlin in question.
The Marlin Firearms Co. New Haven, Conn S.A. Est. 1875
Model 81-DL .22 cal-S-L-LR
And here are the lousy pictures. I know it is a very old rifle. I have never seen sights like this Marlin has, but then again, I am quite a newby to the gun world. Also, I have removed the rust from this rifle with 0000 steel wool dipped in some oil. I have also learned to undo 'that big screw' and take the barrel off the stock to further clean the barrel.
looks like you did a fantastic job cleaning it up! good job. maybe some of our more knowledgeable members will chime in and help us determine more information on that rifle.