Again based on the Ford F-Series, the 1980–1986 Bronco is based upon the Ford F-150 (1980–1986 seventh generation). Although based on an all-new chassis, the Bronco retained its 104 in (2,642 mm) wheelbase. Ford engineers attempting to get as much fuel economy from weight reduction of 375 lb (170 kg) curb weight from the previous year, the 1980-81 models had a much weaker frame with holes stamped out at the factory.[26] This extra lightened frame was dropped in 1982 for more strength and rigidity gaining 31 lb (14 kg) curb weight. Both transfer cases were replaced with a New Process 208 or Borg Warner 1345 version. In front, the 1980–1986 Bronco is fitted with a Dana 44 front axle with Ford TTB (Twin Traction Beam) independent front suspension.[18] As with the 1978–1979 Bronco, the rear axle was first a leaf-sprung Ford 9-inch axle in early models, however Ford transitioned all half ton trucks to their 8.8 rear axle by the end of 1986.