Developed specifically for NASCAR racing, the Superbird, a modified Road Runner, was Plymouth’s follow-on design to the Charger Daytona fielded by sister company Dodge in the previous season. Chrysler memos of September 1969 show that the Sales Programming staff was preparing to handle 1,920 winged Plymouths for 1970, but published figures say as many as 2,783 were built. The current figure generally accepted is 1,935 SuperBirds built and shipped to United States dealers, with anywhere from 34 to 47 allegedly heading towards Canada. The engine option question is again a sticky one, although the most frequently seen numbers report 135 426ci. Hemi SuperBirds and 716 440ci. Six-Pack editions, with the remainder powered by 440ci. 4bbl. motors. It is believed that over 1,000 Plymouth SuperBirds exist today.