In 1959, Rolex launched an important model ref.1600/1601 to enrich the family of Datejust collection. The ref.1601 basically determined the appearance of modern Datejust. You will see that the fluted bezel, hands, hour markers, cases and iconic cyclops lens are almost the same with modern perfect fake Rolex Datejust.
The vintage ref.1601 also maintains the 36 mm case and it was produced from the year 1959 to 1977. In 1970s, Rolex released the new Datejust ref.16000. The impressive update of these Datejust must be the new Cal.3035 movement. Equipped with the 3035 movement, the classical 36 mm Rolex knockoff watches are more convenient.
Then till 1988, Rolex launched the new Datejust ref.16200/16233, which were equipped with the famous Cal.3135. I think many people are familiar with the movement Cal.3135. Meanwhile, you will also see many vintage ref.162XX models of Datejust in secondary market.