 The SD35 and SDP35 were so similar that EMD published a single operator's manual to cover both.Although SAL successfully used the SDP35 in high-speed passenger service as well as on expedited freight and piggyback trains, Union Pacific found it unsuitable and relegated its entire fleet to freight service while its famous yellow E-units continued to handle passengers.With the July 1, 1967 Seaboard Coast Line merger, SAL units received passenger numbers 601-620 and also served SCL in both high-speed freight service and on passenger trains.