6245-9000 Seikomatic Chronometer.
Dial states "Chronometer," it's a dead ringer for the 62GS and it has the GS Medallion,
but technically, its not a Grand Seiko. Mine is from Feb 1966, around the time the Swiss decreed that watches had to be tested in Switzerland to qualify as "Chronometers". So Seiko, in a "one finger salute," created the Grand Seiko Standard. If this exact watch was later in 1966 (Seiko says 1967, but there are 1966 GS62s), it would have been labeled a GS. Mine, unserviced, arrived keeping +10s/d with 230Amp and 0.0BE, which would have qualified as a Swiss Chronometer in 1966 (but not the GS Standard which was about to be rolled out, which was +5/-3s/d).