I own this typewriter; it was originally bought and used by my father. I also used it during the 1970s when I was in school. The serial number is EQR376208T, but it is located in a different position: on the left side, on the inner face of the vertical plate near the ribbon spool. According to the database, serial EQR339939 was manufactured in 1958 and EQR406279 in 1959.