From Ford press: In 1965, the Shelby GT350 was introduced, with a 306 horsepower V-8 engine, giving the Mustang performance credibility.
Mustang sales passed the one million mark in March of 1966. The 1966 Mustang was the first – and perhaps the only – car to park on the 86th floor observation deck of New York’s Empire State Building. Ford engineers disassembled a 1966 Mustang convertible and took it up in four sections using the building’s passenger elevators.
Mustang-mania hit full force. The 289-cid V-8 “Hi-Po” engine became available. Carroll Shelby adapted the Shelby GT350 for Sports Car Club of America (SCCA) competition, and the GT350 went on to win three straight SCCA national championships.
The 1967 Mustang was considered by many to be the high water mark for Mustang design in the 1960s. The 2+2 model went from a semi-notchback to a sweeping full fastback roofline. Separate triple tail lamps, a longer nose and a bigger grille made for a more aggressive stance.
In 1968, the 428 Cobra Jet engine was introduced as part of an option package aimed at enthusiasts, and it helped make the Shelby GT500 become King of the Road – KR.
A “steed for every need” philosophy yielded 11 different powertrain combinations in 1969. New models added to the lineup included hot rods like the 290 horsepower Boss 302, the 375 horsepower Boss 429 and the Mach 1, giving the Mustang its muscle car heritage. The Grande luxury model also was introduced.