If it's a solid rib gun, it would be 1948 for the year of production. 20 ga. deluxe models are quite rare and fetch whatever the market can bear. I don't know (or care) what the blue book says about them. One in 98% condition can fetch over $1,000 and, again, whatever the market will bear. I'm sure somebody else can price it out for Blue Book value.
How much finish is present? Scratches? Aftermarket alterations? Wood condition? Recoil pad? Original recoil pad? Polychoke? All these things will effect value. One man's 80% all original is another man's 98%. 80% finish on an abused, refinished, or altered gun is worth about an 80% reduction in value!