https://rolexhaven.com/hands.html provides good input on hands, including:
"13mm were intended for Small Crowns 6204, 3205, 6536-1 and 5508. It was also the size used on other Sport Models with the Chapter Ring also known as "Closed" minute tracks. This would include the GMT Master 6542 and 1675 as well as the Explorers 6610 and 1016. This length ceased to exist in 1963 when the Chapter Ring minute track design was eliminated from the GMT Master and Explorer references."
... and ...
"12mm hands were introduced in 1963 and used thereafter. The Chapter Ring design was phased out and replaced with the "Open" minute track the same year this size was introduced. With this evolution, the radius of the minute track became constant across all three lines of Submariner, GMT and Explorer models. Therefore, the Submariner (5512/5513), GMT 1675 and Explorer 1016 all use this new size, eliminating the need for the previous two lengths altogether."