This 6246 was produced on 1966 at Suwa Seikosha and was the second "GS" automatic model. 6246 was originally sold as a Seikomatic Chronometer but because of Chronometer appeal, the name was changed to 62Grand Seiko. Therefore, 6246A movement has Seiko internal GS standard official approval.
Below photo shows the earlier version with the chronometer
6246A movement has 39 jewels and has slow amplitude of 19800 beats per hour. Compared to other GSs, there were differences in the position of crown and case design making it a comfort to wear.
There were two kind of case back with the lion back being the rarer one.