As Mike noted, the Seiko caliber 4500 in the King Seiko 45KS also powered some incredible Grand Seiko watches, such as the 45GS (modified). In fact, Daini Seikosha (where King Seiko was made), ...

These watches were part of the catalog from 1969 until 1975 and are famous among Grand Seiko enthusiasts. Driven by the intra-company “rivalry” between the Suwa and Daini Seikosha factories, the V.F.A ...