Originally sold alongside the F-100, the Ford F-150 was created to dodge stricter emissions requirements, Carlson tells us. The EPA required catalytic converters on vehicles with a gross weight rating -- a vehicle's total weight including the maximum amount of cargo -- of less than 6,000 pounds. The F-150 was rated at 6,050 pounds so unlike the lighter-weight F-100 the F-150 didn't require the emission reducing add-on.