GMT 1675, 50XXXXX, Mark IV dial, circa 1976

[springer]

The first photo with Mark IV printed at to the bottom is from a 1974 4.2XXXXX GMT 1675 .

The second photo of the complete watch head wears a Mark IV dial, serial number 50XXXXX, circa 1976/77 with the original insert.

A quick way to identify the Mark IV dials from the other non service matte dials is the alignment of the letters in CERTIFIED underneath the alignment of the letters from CHRONOMETER and how the alignment of the letters from each word correspond to each other.