For 1972 Piper introduced the six/seven-seat Piper PA-34 Seneca which, basically, was a twin-engine version of the Cherokee SIX with retractable tricycle landing gear, a new fuselage structure and power provided by two 149kW Avco Lycoming IO-360 flat-four engines. For 1975 149kW Continental TSIO-360-E turbocharged and counter-rotating engines were introduced and the landing gear was streng-, thened for operation at higher gross weight, the designation then changing to PA-34-200T Seneca II. In 1982 the Seneca II was superseded by an improved PA-34-220T Seneca III, and this remains the current production version in 1984. It differs from its immediate predecessor by having more powerful Continental TSIO-360-KB turbocharged and counter-rotating flat-six piston engines. During 1976-77 Piper signed an agreement with the Polish foreign trade association Pezetel under which P.Z.L. Mielec will assemble/manufacture the Seneca for sale in eastern Europe. Designated in Poland as the P.Z.L. Mielec M-20 Mewa (gull), the first Polish-built prototype was flown on 25 July 1979. Current production version is the M-20 03 one of the very few light-twins on the market. A total of 4,464 Seneca were delivered by 1 January 1991.