First Gottlieb game convertible from replay to add-a-ball operation. This playfield was produced by Gottlieb for the following electro-mechanical games : a 1-player replay version called Gottlieb's 1975 'El Dorado', a 1-player add-a-ball version called Gottlieb's 1975 'Gold Strike', a 1-player add-a-ball version for Italy called Gottlieb's 1975 'Lucky Strike', a 4-player replay version called Gottlieb's 1976 'Target Alpha', a 4-player replay version for France called Gottlieb's 1976 'Canada Dry', and a 2-player replay version called Gottlieb's 1977 'Solar City'. Also later produced as a 4-player solid-state game Premier's 1984 'El Dorado City of Gold'. We have increased our confirmed production run quantity of 7,285 to include 182 Sample games produced in 1976 that were not part of the former quantity per handwritten documentation identified by Wayne Neyens as coming from Bob Malvasio, a draftsman for Gottlieb whose initials RHM can be found on schematics. Of the 7,285 Production games made, Malvasio indicates that 3,343 were made in 1976 and 3,942 were made in 1977.