This post is in response to a question posed by GT-Craig back in late 2021, asking if anyone knew how many 1966 K-Code GT Fastbacks were produced. There were no replies. Since then, as the owner of a 1965 (not '66) K-Code GT Fastback myself, I have given the question much thought and research. While there can be no definitive answer (production records being long gone), I think I can offer a reasonably informed "guestimate".
Specifically to GT-Craig's question, I believe that probably between 700 and 1000 K-Code GT Fastbacks were produced in 1966. Taking both 1965 & 1966 production years together, I would estimate that anywhere from 2000 to 3000 total K-Code GT Fastbacks were produced, with more made in 1965 (1300 to 2000) than 1966 (700 to 1000).
Unless anyone really wants to know, I will spare you all my calculations--- though the math is easy, the assumptions the calculations are based on are complicated and subject to interpretation and dispute. Nevertheless, I am comfortable with my conclusions.
Let me know if anyone wants more info. But be careful what you wish for!