In 1976, a heavily built 1967 Plymouth Barracuda Formula S with a 383 big block got its doors blown off on Gratiot Avenue — by a full-size Pontiac most street racers wouldn’t have recognized. The culprit was a rare 1966 Pontiac 2+2 running a 421 tri-power engine rated at 376 horsepower, a model Pontiac once marketed as the GTO’s big brother. Read on to see how one of the rarest Pontiacs of the 1960s humbled a genuinely fast Mopar.