The standard, or Base Model, offering for the 1971-1973 First Generation Mustang was introduced for 1971, and was available in Hardtop, Convertible, or Fastback (SportsRoof) body styles. The 1971-1973 Base Model Mustang was available with a wide range of engines, yet these powerplants saw their respective power ratings drop in 1972 due to increased emissions regulations. The "L-code" 250 cubic inch (4.1L) inline six was the standard engine, while a range of optional V8s were offered. These V8 engines were available in various displacements and carburetor setups, and consisted of the "F-code" two-barrel 302 (4.9L), the "H-code" two-barrel 351 (5.8L), the "M-code" four-barrel 351 (5.8L), and the "Q-code" four-barrel 351 (5.8L). In addition to these small block V8 engines, in 1971, Ford offered two big block options: the 370hp "C-code" four-barrel 'Cobra Jet' 429 (7.0L), and the 375hp "J-code" four-barrel 'Super Cobra Jet' 429 (7.0L). For the 1972 model year, the V8 engine options were changed, with the big block V8s no longer offered, and the introduction of the "R-code" HO four-barrel 351 (5.8L) V8. This low compression "R-code" HO 351 is not to be confused with the "R-code" 351 that was equipped in the 1971-exclusive Mustang Boss 351. The low compression "R-code" was only available in 1972, leaving the "Q-code" 351 as the top engine for 1973. Depending on the selected engine, 3 speed manual, 4 speed manual, or 3 speed automatic transmissions were available, all of which sent drive to the rear wheels. The 1971-1973 Ford Mustang was the final iteration of the First Generation Ford Mustang, as the Second Generation Ford Mustang (Mustang II) debuted for the 1974 model year.