From what I've read, a 1964 NM Pistol should (key word, "should") have a barrel marked with the part number "7791414". However, is it possible for a '64 to have a barrel marked "7790313", (the earlier version) and still be as issued from SA? The barrel in question is serially numbered (all digits) to the frame. The pistol in question is in a 7/64 dated box and has the proper "Drake" slidefor 1964. Everything else appears to be as it should. Thanks !!!