GS models

From the internet, we can see that before the mechanical GS line of production was resurrected in 1990s, Seiko had introduced 8 main GS models during approx. 10-year period (60-70). 

As there were variations in some GS models, below is based on the formal designated models.

 1) GS First Model ("GS3180" Hand-Wound 18,000 vph)
Manufacturer: Seiko Suwa
Production Start: 1960
Production End (approx.): 1963-64 

2.1) GS Second Model ("GS430 Self-Dater" Hand-Wound 18,000 vph)
Manufacturer: Seiko Suwa
Production Start: 1963
Production End (approx.): 1965-66

2.2) GS Second Model ("GS57 Calendar" Hand-Wound 19,800 vph)
Manufacturer: Seiko Suwa
Production Start: 1966
Production End (approx.): 1968-69 

3) GS Third Model ("GS44" Hand-Wound 18,000 vph)
Manufacturer: Seiko Kameido
Production Start: 1966
Production End (approx.): 1967-68

4) GS Fourth Model ("GS62" Automatic 19,800 vph)
Manufacturer: Seiko Suwannee

Production Start: 1967

Production End (approx.): 1968-69

Winding crown at 4 o'clock position.

5) GS45 (Hand-Wound 36,000 vph)

Manufacturer: Seiko Kameido 

Production Start: 1968

Production End (approx.): 1971-72

6) GS61 (Automatic 36,000 vph)=> mass production
Manufacturer: Seiko Suwa
Production Start: 1967
Production End (approx.): 1975-76

1st Generation GS6146 from 1967

2nd Generation GS6146 from 1969

7) GS56 (Automatic 28,800 vph)=> mass production
Manufacturer: Seiko Suwa
Production Start: 1970
Production End (approx.): 1974-75