1969 is where the first generation peaked at once: the most extreme factory engines (the all-aluminum COPO 9560 ZL1 and the iron L72 COPO 9561), a second Indy 500 pace-car turn, all-new sheet metal, and the last year before a total redesign.
It also carries the corpus's most stubborn production dispute: the 1969 Z/28 total is cited as both 19,014 and 20,302, and even the Camaro Research Group's own page only narrows it to a range.