In 1965, the F-Series began to offer a 4-door crew cab as an option. Additionally that year, the Ranger name made its first appearance on a Ford truck; previously a base model of the Edsel, it was now used to denote a high-level styling package for F-Series pickups. A new chassis also marked the first appearance of Twin I-Beam front suspension.
The fourth generation Ford F-Series was a line of pickup trucks and commercial trucks produced from 1961 to 1966 by Ford Motor Company. Lower and wider than its predecessor, the new F-Series introduced several firsts to the truck line. In Canada, the F-Series continued to be distributed by Mercury dealers as the M-Series.
Along with the traditional separate Styleside/Flareside boxes, Ford introduced unibody trucks; these integrated the cab and the box into a single body.
Due to poor market reception, the unibody trucks were dropped after 1963.
While the body remained largely unchanged, the 1965 F-Series was given an all-new chassis. This would go on to underpin the F-Series until 1979; consequently, many parts from 1965–1979 interchange such as brakes and motor mounts. An all-new Twin I-Beam front suspension was introduced with coil springs; 1965-1966 F-Series trucks are distinguished a “TWIN I-BEAM” emblem on the front fender. Twin I-Beam front suspension would go on to be adopted across the light-duty Ford truck lineup and is still in use in the 2013 E-Series vans. To give the 1965 F-Series the same passenger capacity as the majority of its car lineup, the F-Series now included a 4-door crew-cab model.
In 1965, the 300-cubic inch (4.9 L) straight six was introduced (a larger version of the 240-cubic inch Six). It had 7 main bearings and timing gears (no chain or belt). The 300 six would remain in the F-Series lineup until the end of the 1996 model year. With the introduction of the 208-hp FE V8, output surpassed 200 hp in the F-Series for the first time.
F-100 (F10, F11, F14): 1/2 ton (4,000–5,000 GVWR max)
F-100 (F18, F19)(4×4): 1/2 ton (4,000–5,600 GVWR max)
F-250 (F25): 3/4 ton (7,400 GVWR max)
F-250 (F26)(4×4): 3/4 ton (4,900 GVWR max)
F-350 (F35): 1 ton (9,800 GVWR max)
The Camper Special was built heavier for the slide in campers that were becoming increasingly popular during this time. Ford still offered a “Low GVWR” version of each model. In 1965, the Ranger name first appeared as a styling package for the F-Series pickup trucks. The interior featured bucket seats (from the Mustang) and a curtain over the gas tank which was behind the seats in the cab.
source: http://en.wikipedia.org/wiki/Ford_F-Series and http://www.youtube.com