That's the way Fisher did it. You'd have to get the "why" from the production people who did it in 69. Only idea I can think of as a possibility is that it might have something to do with nearing the end of the year production. But who knows? There is not a consistent pattern of week dates on the trim tags throughout the whole production year; Some months have "A" through "D", some months skip from "A" to "C", etc. The purpose of the Tags was scheduling, so as long as that was being accomplished, probably no one cared about anything else.