Conrail inherited 32 SDP45s from the Erie Lackawanna, reassigning their EL series 3635-3668 to CR 6667-6699.
Built from May, 1969 through August, 1970 for the EL, EMD added a longer frame for concrete ballast aft of the radiators and a larger fuel tank for greater range. EMD's turbocharged V20 20-645-E3 prime mover produced 3,600hp.
As EL was under control of the N&W when the original series 3635-3653 was ordered, Conrail returned them in 1984 to the Norfolk Southern. EL's second order series 3654-3668 were returned to their lessor on January, 1984