Complex sentence: Based on the heavy-duty, full-size Super Duty line of trucks, the Excursion was Ford's largest SUV in its lineup, and the largest and heaviest on the North American market during the tenure of its production.
Split into simpler sentences: Based on the heavy-duty, full-size Super Duty line of trucks. The Excursion was Ford's largest SUV in its lineup, and the largest and heaviest on the North American market during the tenure of its production.