going back to the well with the same chassis as before
Very vaguely based on profiles drawn by Joshua Moldover, via The Railroad Paint Shop and yours truly @ my dining room table
When the EPA’s emission standards for new locomotives came into effect, it made everything all topsy-turvy for the workers at the MTRR’s Iberville Locomotive Works; they’d built up a shocking amount of expertise on maintaining and tuning the Alco 251, but were unable to reliably get their 251 test beds to get near Tier 4 emissions without a lot of exhaustion and were faced with needing to convert to someone else’s prime mover.
One of them was the Cummins QSK45, which was put into demonstrator 618, a machine that was one of the very first rsx51s built (1978); it had been traded back to ILW in 2010 for an e636, but was in mechanically good enough shape to store for eventual rebuild, and that rebuild was to make it into this demonstrator. Downrated to 1800 HP, but with a pure AC transmission to make up for some of it.