I recently acquired a book of airline poster art, "The Art of the
Airways" by Geza Szurovy. Toward the end, on page 175, there is a
Delta Air Lines poster advertising travel to Detroit, showing an
artist's conception of an advanced car design on a drawing pad,
surrounded by drafting instruments: a pencil, a triangle, a French-
curve protractor, and a slide rule, which is easily recognizable as an
Acu-Math 400.

No date is given for the poster, alas, but a variety of indicators
(including, obviously, the slide rule itself) suggest it dates to the
late 1970s.