The four-axle GE B36-7 was a high-horsepower speed racer built to appeal to railroads in the early 1980s looking to turbocharge their growing intermodal business. There were few drag freights or slow-moving manifests for these thoroughbreds in their early years. They could be found in multiples at the head of piggyback and autorack services and the new double-stack container trains.
Replacing the "Universal Series" U36B in the GE catalogue, the first prototypes were built at Erie, Pennsylvania, in 1980 for the St Louis SouthWestern, otherwise known as the Cotton Belt. Initial orders were hampered by the recession of 1981-2; however, by the last year of production in 1985 some 222 locomotives had been constructed for US railroads with a further eight for export. We were surprised to find that this wasn't that far off the total of GP50s ever built, yet we've seen three HO scale models of that so far!
The design found customers in several of the larger Class 1s of the period: Santa Fe, Conrail, Seaboard System, Southern and Southern Pacific. With the mergers of the mid-1980s and the Conrail split of 1999 the bulk of the fleet ended up with CSX and Norfolk Southern. Circa 2000 the CSX roster was overflowing with B36-7s, with around 140 former Conrail and Seaboard units operating all over the eastern half of the US. The ex-Seaboard fleet was officially retired towards the end of 2009, but examples were still working into 2011. They even still have some on the property. If your're a Seaboard or CSX modeler you need at least ten of these things!
The turbocharged 16-cylinder 7FDL prime mover rated at 3,600hp (later examples could create up to 3,750hp) and upgraded alternator and traction motors proved to be a reliable combination. However, with all that power on tap and with just eight wheels to lay it all down they gained a reputation for shaking the fillings out of teeth and marrow from bones. They were well liked by railfans though and were among the last of the Dash 7s in Class 1 service, outliving the six-axle variants by a number of years.
The increased power also meant increased noise. As well as the larger silencer (introduced in 1979), GE attempted to mitigate this with a pair of sound baffles either side of the radiator section. These were installed on all the Cotton Belt, Santa Fe and Southern locomotives and the first 15 Conrail units. By 1983 GE had replaced the twin radiator fans with a single large fan to reduce noise - three additional grilles in the doors in the radiator section made this upgrade obvious - and only Southern retained the baffles beyond 1986, and even then only the lower of the two on each side. The Rapido model correctly replicates ALL of these details as appropriate.