The first Domino's Air-King ref. 5500 had a "big logo" at six o'clock. In these early years, Domino's would also engrave the recipient's initials as well as "TSM" (for founder Thomas Steven Monaghan) on the caseback. Even the papers are
link made out to "Domino's Pizza." It's a bonus to find a Domino's dial in a case that still has its full caseback engraving to
link legitimize its provenance and originality. This personalized caseback engraving later changed to an
link engraving of the Domino's domino.