Don 't recall nor do I have any pictures of those paint markings on 70's Dearborn or other plants on Mustangs. Will double check my pictures over th enext couple of days - still have family around for the holidays
Maybe someone else has a picture of one or both of them on an original car.
Good thing to ask about since it's not uncommon for marks to be different or just being marked at all on replacement parts verses assembly line parts and for restorers to copy the replacement markings just because