From Jody Moore on August 23, 2007: "The unit that is headed up to Alaska for demo is not a hybrid locomotive, but what is called a genset locomotive, with two smaller engines instead of one large on, and the ability to turn engines on an off at will as needed. The particular locomotive, NREX 2007, is a two engine, 1,400hp model 2GS14B built by National Railway Equipment (NRE). They also make a three engine, 2,100 hp model 3GS21B. Union Pacific has gotten 60 of those. These aren't to be confused with Railpower's hybrid "Green Goat" models, which use a single engine to charge a battery bank for propulsion power. Railpower also makes similar "genset" models, mainly their three engine RP20BD, and their twin engine RP14BD."

From Tim Thompson, ARR Public Affairs on August 22, 2007: "We are going to try the switcher out for a couple of weeks after its arrival sometime in the next few weeks. As you are probably aware this is a diesel/electric hybrid. That is all the information I have at this time."