opened after the front doors are open. Other modern extended-cab trucks have small conventional rear doors such as the Ram Pickup and Toyota Tundra. A crew cab, or double cab, seats five or six and has four full-sized, front-hinged doors. The first crew cab truck in the United States was made by International Harvester in 1957, and was later followed by Dodge in 1963, Ford in 1965, and Chevrolet in 1973. Cab-over or cab forward designs have the cab sitting above the front axle. This arrangement allows a longer cargo area for the same overall length. An early cab-forward, drop-sided pickup was the Volkswagen Transporter, introduced in 1952. This configuration is more common among European and Japanese manufacturers than in North America. The design was more popular in North America in the 1950s and '60s, with examples including the Chevrolet Corvair Rampside and Loadside, Dodge A-100 and A-108, Ford Econoline, and Jeep FC-150 and FC-170. The cargo bed can vary in size according to whether the vehicle is optimized for cargo utility or passenger comfort. Most have fixed side walls and a hinged tailgate. Cargo beds are normally found in two styles: step side or fleet side. A step-side bed has fenders that extend on the outside of the cargo area. A fleet-side bed has wheel wells inside the bed. The first fleet-sided truck was the 1955 Chevrolet Cameo Carrier. Early trucks had wood-plank beds, which were largely replaced by steel by the 1960s. Some European-style trucks use a drop-sided bed with a flat tray with hinged panels rising up on the sides and the rear. A "dually" is a North American colloquial term for a pickup with four rear wheels instead of two, able to carry more weight over the rear axle. Vehicles similar to the pickup include the coupé utility, a car-based pickup, and the larger sport utility truck (SUT), based on a sport utility vehicle (SUV). The terms half-ton and three-quarter-ton are remnants from a time when the number referred to the maximum cargo capacity by weight. The last time Chevrolet and GMC used the Stepside style was on the 2007 Silverado and Sierra Classic models. Ford last used the Flareside style in the 2009 F-150. Uses In the United States and Canada, pickups are used primarily for passenger transport. Pickup trucks are often marketed and used for their hauling (utilizing cargo bed) and towing (utilizing body