I don't have any idea about the 2 and 3 stamped with the serial numbers. The gun is very coveted with original hard butt, long tang, round knob stock and early serial number. Yes, it is post war, as are all 20 gauges. The case is not proper for the gun and adds little value. A matching number two barrel set is scarce and valuable, maybe $3600 to $4000. 1955 gun probably, full and full 28" is scarce to rare. I had one, same era, but the chokes had been opened. I sold it for $2100 because of the opened chokes and non original recoil pad. I would kill for an early full and full 28" gun with the chokes intact.