You should note that setting up in 2005, Rolex commenced engraving the serial variety within the interior bezel (also called the rehaut) under the crystal within the 6 o’clock position. Though the crystals to the 160xx generation of Datejust watches are still made out of acrylic, the sloped "pie pan" https://www.watchesworld.com/a-history-of-watch-reference-numbers/