There is nothing about the EMD DDA40X that is not unusual. Just looking at the picture above, it is easy to tell that this is probably the largest of any other diesel locomotive, considering the fact that it's basically two locomotive combined as one. Having been built at a time of competition between GE and EMD for the locomotive with the most horsepower, the DDA40X is probably also the most powerful of any other diesel locomotive. Its 6,600 horsepower (over the GE AC6000's 6,000 horsepower) proves the point! 47 examples of the DDA40X were built. However, there is currently only one DDA40X in operation...UP 6936 (shown above). The reason for this is that the DDA40X was not really suited for american railroads. Because of its size, the DDA40X needed larger 4-axle trucks over the 3-axle trucks of average locomotives. Since no other locomotives were built with 4-axle trucks and the DDA40X is much longer than your average locomotive (at 98 ft), it has trouble getting around some of the sharper turns of America's railroads. Overall, the DDA40X was a good idea in terms of horsepower, but not a very good idea in terms of being practical (which is probably why there is only one in operation)!
The MP36PH-3C is part of a series of locomotives built by MP (Motive Power) called the "MPXpress" series. This group, which consists of the MP36PH-3C, MP36PH-3S, and the MP40PH-3C, was specifically designed to pull passenger trains on commuter railroads. Indeed, you will never see any of these locomotives in freight service. Caltrain, FrontRunner, MARC, Metrolink, North Star Line, New Mexico Rail Runner, Virginia Railway Express, and the West Coast Express all own fleets of MP36PH-3Cs. Caltrain was the first commuter railroad to purchase a fleet of these locomotives in 2003 to pull its "Baby Bullet" express trains. The photo above shows a Caltrain MP36PH-3C on a Baby Bullet train.
Similar to the EMD F59PHI in appearance, the MP36PH-3C, however, is a good deal longer and has different spotting features than the F59PHI including:
1. Fuel tanks are clearly visible underneath the locomotive.
2. Three air tanks positioned in front of the fuel tanks.
3. Smaller and wider plow on the front than that of the F59PHI.
4. A more streamlined-looking nose - similar headlights to the F59PHI.