The director, the late Tony Scott, and his team who worked on the trains themselves stated they had 3 or 4 1206 locomotives. One of them was a modified, unpowered version they called the "buck" model so they could do those superb 360 degree camera shots of Denzel and Chris in the cab.
They also had 2 777's, 2 767's, and 2 of each of the gray SD40-2's used in the middle of the movie. One of those pair were scrapped locomotives hollowed out and repainted for the derailment scene.
