I believe this to be a 1967 Sea King AD almost identical to https://mybulova.com/watches/1967-sea-king-ad-7865 with the red 24 printing. The movement is a 17 Jewel 11ALC movement. I believe the date code on the movement is M6, but I cannot be sure, even with a loupe. The listing of the other example theorizes that the red dial printing was custom by the owner. With 2 of these, I am wondering if the printing could have been a custom run by Bulova?
Interesting, I hadn’t thought of the Vietnam/Military aspect. I was doing some investigation and notice the Red 24 dials of the Accutron Railroad watches. At closer look the Font, size and overall diameter are the same. With the 2 photos I had all printing lines up. Admittedly the photos are not perfect. Maybe this was a standard printing die of the time or Bulova shops could order the die? Maybe it was some kink of custom run for RR execs that wanted a dressier watch? Probably never find the answer but mystery is fun.