From Ford press: The 1964 Thunderbird reverted partially to the square design theme. It was more angular than the 1961-63 models, yet not as square as the 1958-60 models. The new styling featured a longer hood, a shorter roofline and sculptured side panels. With the bumper and grille designed to provide a faster, more aerodynamic look, the overall styling continued Thunderbird’s by-now traditional image of "swift-lined sleekness."
Though the design for the 4,760-pound car was essentially the same as 1964-65 models, the 1966 Thunderbird became a collector's favorite because it is regarded as the best of the four-seaters of the era. Ford discontinued the Thunderbird convertible after the 1966 model year. Not counting the two-seaters 70,244 were produced. 1966 marked the end of Thunderbird's youth, but many of those young 'birds would live on tucked safely away in garages across America.