Premise: The sixth generation of the Ford Thunderbird is a large personal luxury coupe that was produced by Ford for the 1972 to 1976 model years. A counterpart of the Lincoln Continental Mark IV, this generation of the Thunderbird was the largest ever produced; weighing in at over 5000 lb , they are also the heaviest coupes ever produced by Ford (aside from its Mark IV counterpart).
Hypothesis: The sixth generation of the Ford Thunderbird was not actually produced by Ford.