The B-24E was essentially an updated version of the D-model with some minor modifications. Most B-24Es were equipped with Pratt & Whitney R-1830-65 radial engines with improved propeller blades, though Douglas-built versions had R-1830-43 engines. This model marked the entry of the Ford Motor Company at Willow Run, Michigan, into B-24 production. The constant production changes on various Liberator lines frustrated Henry Ford, an advocate of American mass-production techniques. He slightly redesigned the aircraft to fit his concept of a moving production line, where different components were added at specific stages. In total, only 801 B-24Es were built, with Ford producing 490, Tulsa 167, and Fort Worth 144.