Serial Range: 516xxx-596xxx
The first 1016 dial is the easiest to pick out. It is the only dial variation that carries over the movement certification from the 6610, “officially certified / chronometer” (often referred to as ‘OCC’). After this, the rest of the 1016 model variations are marked “superlative chronometer / officially certified,” consistent with the upgrade from the 10xx calibre line of movements to the 15xx line. The specific upgrade for the Explorer line was from the 1030 to the 1560 calibre movement. Unlike the OCC Dial GMT 1675, which has a transitional movement between the 6542 GMT and the standard 1675 (the 1530) the early 1016’s appear to be fitted with the standard 1560 movements from the start. Of note, the dials between the 6610 and the 1016 are not interchangeable as the dial feet and diameter are different to accommodate this new movement and slight changes in the case.
The Tell: As mentioned above, these dials are unique because of the font on the dial. Therefore, you don’t need to look at the variations in crown or font for identification, just look for the OCC on the dial. There are some aftermarket OCC dials floating around (I’ve seen more for 6610’s and therefore the dial feet are incorrect) so close inspection of the galvanic dial printing is required to make sure they’re original.