Robert, The "RE" that is before your serial number means that it is a Regular frame with ejectors. Just the "R" would mean Regular frame. The "S" means that the serial numbers started over again when Marlin Firearms started producing again in 1946. That is why there is a big jump if you leave the "S" off. There are some guns that have an "R" after the serial number and no one is sure what that means. Also early guns there is a "FW" before the serial number meaning Featherweight frame. Later guns from Marlin had "FW M". After 1946 they only made Featherweight frames. The difference is in the shape of the sideplates, the number of screws holding the sideplates on. A Regular frame there is only one screw, on a Featherweight there are two screws on one side and one on the other. Also the lug that comes through the bottom of the receiver is smaller on the Featherweight. Hope that this helps you.