In the late 1950's the horsepower race was very heated and with the introduction of the 2500hp U25B from General Electric in 1960, EMD was caught short. It took 2 years to play catch-up and the result was the GP30.
Conrail units came from two predecessors that bought or inherited the 2250hp units. Reading ordered 20 units (5501-5520) from EMD in 1962 which became Conrail units 2168-2187. A total of 62 units from NYC and PRR were inherited by Penn Central (2188-2249) and became Conrail units 2188-2249.
The GP30 saw service into the early 1990's throughout the system. The final unit was retired in 1993.