In the meantime, there’s some proof that Intercontinental distributors hated the inconsistent and often illogical numbering systems of their Swiss overlords. Though the crystals to the 160xx generation of Datejust watches remain made out of acrylic, the sloped "pie pan" design dial through the prior era is long gone, and https://www.watchesworld.com/a-history-of-watch-reference-numbers/