The F platform, or F-body, was General Motors' rear-wheel drive pony car automobile platform from 1967 until 2002. It was based partially on the GM X platform, which was used for compact applications instead of the sporting intent of the F-Body. The only two vehicles to have been built using the F-Body platform are the Chevrolet Camaro and the Pontiac Firebird. The fourth character in the Vehicle Identification Number for an F-body car is "F" on model year 1985 and up vehicles. Earlier Camaros and Firebirds had differing VIN codes, but are now commonly referred to as F-bodies. First generation (1967–1969) The first F-body cars were produced in 1966 for the 1967 model year, as GM's response to the Ford Mustang and later the Mercury Cougar. Originally designed strictly as the platform for the Camaro, Pontiac engineers were given a short amount of time prior to the Camaro's release to produce a version that matched their corporate styling as well. The F-Body was available as both a hardtop coupe and a cloth-top convertible. As was GM policy at the time, Chevrolet and Pontiac both installed their own engines; however, the engine lineups were similar. Both cars could be had with either division's base inline six-cylinder engine, a V8 engine of approximately 5.3 liters (327 cu in for Chevrolet, 326 cu in for Pontiac), or a larger V8 engine of approximately 6.6 liters (396 cu in for Chevrolet, 400 cu in for Pontiac). Due to delays with the design of the second-generation car, the 1969 models were produced longer than usual. Second generation (1970–1981) The second generation F-body cars were actually released in February 1970, due to extensive delays in the design and production of the new body style. Both cars grew considerably, with fairly drastic changes in styling to match each brand's updated styling across the lineup. Only Pontiac received engine options in the 7.5 L range in the earlier years of the second generation - (454 cu in for Chevrolet is in technical manuals, but was never produced), 455 cu in for Pontiac. However, this engine option would be discontinued as emissions and fuel-economy restrictions made their production costs prohibitive. Performance continued to decline through 1981, as power levels dropped and weight increased. Third generation (1982–1992) The third generation of the F-Body was introduced for 1982, as a major redesign with a more modern look and a lighter, better-handling