[The serial number starts with an L and then has 5 digits after that.]
An "L" prefixed Marlin serial number indicates a 1952 manufacturing date.
That would make it a Third Model, Second Variation.
Your rifle looks to be a "Mountie" config, but the first Mounties were introduced in 1953.
I suppose that a late 1952 receiver could have been later assembled as a Mountie in 1953 - but I'd want to see what the factory has to say about that.
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