Most of the 301 serial numbers were issued in 1951, but those numbers were used from 1951 through 1954, with largest production runs in 1953 and 1954...and they didn't keep good records of dates when the serial numbers were actually put on machines. So, although yours may come up 1951, chances are it was made 2 or 3 years later. Only the true centennial machines have a special Blue Badge that specifically says Centennial 1851-1951 on it. AND, if it's a 301a, it was made at a different factory, and then it for sure is later than 1951.