The Boeing 757 was developed to replace the 727 on existing routes. It featured a stretched fuselage to carry more passengers than the 727, along with more fuel-efficient turbofan engines. The initial 757-200 variant entered service in 1983 with Eastern Airlines and British Airways, powered by Rolls-Royce or Pratt & Whitney engines. Variants included a package freighter version for UPS and a military passenger version for the US Air Force.