'King Rex' is an Italian add-a-ball version similar to the replay game Bally's 1969 'King Tut'. The manufacturer produced the backglasses in both crystal glass and Plexiglas. This is the first Bally game to use a "dummy zero" as its ones-digit in the score display. Two earlier Bally games, 1965 Fun Cruise and 1966 Deluxe Fun Cruise, used a silkscreened '0' for the ones-digit. Reportedly, the "dummy zero" was not just a plastic score reel segment as was typical of later games but was a full score reel without the mechanism. This plastic reel was kept in place by using an angular piece of metal screwed to the wood of the inside of the backbox. We have no pictures of this dummy reel. Pictured in this listing is an Early Production game with serial number 1054 having cabinet artwork that matches the flyer.