Yes suggested that if you wanted to discuss we not take the focus away from another thread the subject came up in.
Haven't seen any other K code dist with a mark on the information/ID area of the main housing. Do have one A code dist with a yellow mark in the general location.
Do have documentation of slashes or an "X" on the housing about 30 degrees clock wise (from above) Visible with the cap in place.
Not allot of them have remained after so long can become lost (if they were all there in the first place) during a restoration mistaken as something else. And of course the K code has been one of the more commonly restored or refreshed of most of the early model cars suggesting that fewer unrestored examples survived. Do have some other markings that are different from those below but only individuals so can't be sure if they are normal or one off's at this point.
From a period magazine - 1965
From another period magazine road test - 1967