Here's what Wikipedia says:
The first F-series truck from Ford was introduced in 1948, replacing the company's previous car-based pickup line. It was a modern-looking truck with a one-piece windshield and integrated headlights. The F-series was available as three models:
F-1 - half-ton
F-2 - three-quarter-ton
F-3 - Heavy Duty
The F-series was redesigned for 1953 with a more integrated look. The pickups also acquired their familiar names: F-100, F-250, and the heavy-duty F-350.
Fourth generation (1961–1966)
The truck was completely redesigned for 1961 with a wider look, and styleside trucks got an integrated cab and box. Power was over 200 hp with the 1965 refresh of the powertrain. In 1965, the Twin I-Beam front suspension was introduced. The 1965 and 1966 trucks have a "TWIN I-BEAM" emblem on the front fender
Fifth generation (1967–1972)
Another refresh came in 1967 along with a now-familiar name: the upscale Ranger trim line. The front leaf springs were replaced by coil springs in F-100s in 1968 along with a powertrain refresh. A 4-door crew cab version was introduced in 1969, still a popular option. The top trim for 1970 was named Ranger XLT
Sixth generation (1973–1979)
The truck was redesigned in 1973 with an automatic transmission option. Other changes included the 1974 introduction of the extended super cab version. A luxury Lariat trim was introduced for 1978. That same year, the F-series became the best-selling vehicle in America, a position it has continued to hold since
Fifthe generation (1980-1986)
The next major redesign came in 1980. The new truck had a squarer look, with sharp lines and flat panels. The Ranger trim line was dropped in 1982, since that name was to be applied to the new Ford Ranger compact pickup. Trim options were now XL, XLT, and XLT Lariat. The big-block V8 was dropped for 1980, but added again in 1983 along with a Diesel option. The base model was renamed to the now-familiar F-150 for 1984. In 1985 fuel injection became optional in the 5.0L. In 1986 this became the only 5.0L offered.
The 1987 refresh was evolutionary. The design was more streamlined, and maintenance items were made simpler. Rear antilock brakes were now standard, the first truck to boast this. The manual transmission was revised with five speeds in 1988, and the flareside box was dropped. For 1987 the 4.9L had standard fuel injection; for 1988, the 5.8L and 7.5L also gained fuel injection, with 1988 being the first year no carbureted engines were offered. 1988 also saw the replacement of the 6.9L diesel with a 7.3L International Harvester IDI diesel.
Four wheel drive improvements included the addition of automatic locking hubs for the F-150 in 1989, and for the rest in 1991. The 5.0 L truck also had an optional "Touch Drive" electronic transfer case.
Ninth generation (1992–1996)
The 1992 truck was much more rounded and aerodynamic-looking, and the flareside returned until 1996. The Lightning appeared in 1993. A CD player option was new for 1994, as was a driver's-side airbag and "CHMSL" third brake light. Following the lead of the Explorer, an Eddie Bauer trim line was added for 1995.
Tenth generation (1997–2003)
Ford took the aero styling to its conclusion for 1997 with an extremely round nose on the new F-series. The "Super Duty" F series did not yet exist, so an F-250 was offered which was an F-150 with heavier duty axles and suspension, along with odd 7 lug wheels. With the arrival of the Super Duty, this F-250 "light duty" was offered as the "7700" package for the F-150 (noted on the tailgate emblem). A wide variety of body options were available: regular cab and SuperCab, standard or flareside boxes, and short and long beds. A new Lightning was introduced in 1999, and Harley-Davidson and King Ranch versions were also created. In 2001 the SuperCrew cab was introduced.
The super-duty F-250 and F-350 were retained on the old chassis until 1999.
Eleventh generation (2004–)
In 2004, Ford redesigned the F-Series using the new P2 platform. Initially, only Ford's 4.6 L Triton and new 3-valve 5.4 L 3V Triton V8 engines and automatic transmissions were offered on the new luxurious trucks. Work-oriented versions with an available 4.2 L Triton V6 and manual transmission will debut for 2005.
The previous F-150 was continued in production until the summer of 2004 as the Heritage model.
The new F-150 won the North American Truck of the Year award and was Motor Trend magazine's Truck of the Year for 2004. It also beat the three-time winning Chevrolet Silverado for Car and Driver magazine's Best Pickup Truck for 2004 and 2005. Additionally, over 912,000 F-150s were sold in 2004, giving it a single-year sales record.
For 2007, Ford introduced a complement to the existing 4WD FX4 model, the new FX2 Sport package. This truck is a 2 wheel drive truck with an appearance package.