The Last Car Ford Ever Put a 427 In Wasn’t a Mustang — It Was This Forgotten Mercury Cougar by Jack Harmon In 1968, Ford quietly built its final 427 side-oiler into just 357 Mercury Cougars — not Mustangs. This is the story of the GT-E, a sleeper built for buyers who wanted comfort with their horsepower, and why almost nobody remembers it today.