This one is a real beauty. It is a 1969 Bulova Accutron Date & Day (variant unknown). I love the striking black dial with red date wheels and accents plus the up down Date and Day. The case is stainless steel and the date code is M9. I did not open the back but assume it is the standard 2182 Accutron movement. The crystal appears to be a replacement as is the bracelet. Lucked out and got the box too although the warranty cards are for a Bulova 23.
Agree, M-9 218-DD Stainless Case.
Also: The first thing you want to do is open the case and check your battery and voltage. Make sure all the contacts are clean and replace with a fresh 344 button cell. The reason for this is that the wrong batteries are installed half the time that can damage your coils and electronics. On a 218 the battery replacement should be done by a watchmaker.
Enjoy
John V. - Time & Again