This is the last pinball machine from this manufacturer to use a silkscreened '1' for the thousands digit in the score. Subsequent games used a score reel in this position for higher scoring.
The add-a-ball version of this game is Gottlieb's 1967 'Diamond Jack'. The add-a-ball version for export to Italy was Gottlieb's 1967 'Solitaire'. The game was also produced in Spain as Petaco's 1967 'Rey de Diamantes'.