ALCO built 85 examples of its DL-600B or RSD-15 diesel between 1956 and 1960. Original owners of the RSD-15 included: Cotton Belt; Duluth, Missabe and Iron Range; Pennsylvania; Santa Fe; Southern Pacific.

ALCO Models imported both a low hood (D-102) DL-600B and a DL-600B High Hood (D-114).