There's another change here too though – the additional of the "Superlative Chronometer / Officially Certified" text to the bottom of the dial. link It was right around the time that this watch was made that the reference 5513, which was Rolex's non-chronometer Submariner, started rolling off the line. These extra two lines of text were the main way that you could tell the two references apart from one another going forward. We'll have a lot more on this below. Stay with me.