The ref. 1603 is the quintessential vintage Datejust. Though the model family dates back to 1945, it wasn't until the late 1950s when the cal. 1560 was introduced, being given the 1603 reference number. These watches introduced the now-iconic baton hands and stick indices, which are today the standard configuration for the model. The 1603 came with a steel engine-turned bezel, which embraced the aesthetic pop it gave while moving away from more the more complex design choices of earlier models.
eBay