Watches would change forever upon the arrival of quartz in the 1970’s, and it’s interesting to see how quartz-watch technology evolved, especially for Rolex. The first quartz equivalent of the men’s watch caliber came in two versions; the functions of Caliber 5035 were hours, minutes, sweep seconds hand, and date. Caliber 5055 featured the day/date function, which also explains the difference in height. Both Calibers featured a tuning-fork-type, mechanically cut 32-kHz quartz resonator made by NDK in Japan.
Read the full story here :: When Rolex Went Quartz: A Tale of the 1970s