GP20s The Union Pacific received 30 production EMD GP20s in July and August, 1960. They were originally numbered 700-729, but were renumbered 470-499 in December 1962 and January 1963, so that the 700 series could be made available for more GP30s. Although 30 was a fairly small number of units for any model on the UP, the railroad had initiated an experimental program of turbocharging its Phase III GP9s. Turbocharching the normally aspirated (actually "blown") 1750 horsepower GP9 engine resulted in a 2000 horsepower unit. These units, called "Omaha GP20s", were the immediate precursors to the EMD standard turbocharged GP20 model. UP listed the "Omaha GP20s" with the EMD GP20s in employee timetables and gave them the same tonnage ratings. However, UP referred to "Omaha GP20s" as GP9ms. A UP employee timetable lists GP9m units as 300, 303B, 304, 305, 307, 307B, 308, 308B, 311, 313, 316, 317, 318B, 320, 325, 325B, 326, 328, 329, 330, 332, 334, 334B, 335, 335B, 337B, 338, 338B, 340, 340B, 343, 344, 347, 348, and 348B. The "Omaha GP20s" did not look like EMD GP20s, and they differed in appearance within the group depending on what type of turbocharger had been installed and whether the fuel tank had been modified for Bunker C oil. In the late 1950s, Union Pacific and other Western railroads discovered the need for higher horsepower diesel units. Diesels allowed longer freight trains, while competition among the railroads required faster freight schedules. While EMD offered the 2000 horsepower GP20 to meet this need, General Electric was developing the 2500 horsepower U25B. The result was the "horsepower race" among diesel builders in the 1960s, and the GP20 was quickly superseded in EMD's range by the 2250 horsepower GP30. Once UP had acquired a large number of higher-horsepower units, the relatively lower-horsepower GP20 began to display the high maintenance costs of a turbocharged unit, but with the horsepower of a non-turbocharged GP38-2. As a result, UP began to sell or scrap the units in 1977. Many of the units were in good condition and were sold for further service by other owners. GP20s operated in general freight service over all UP main lines in the 1960s and 1970s. They could be seen in the very large locomotive consists made up of different models and different builders that typefied the "Unlimited Power" UP of the 1960s and 1970s. In later years, they could be found in local freight service. Photos indicate that the EMD GP20s arrived from the builder with Leslie horns mounted centered on the cab roof front. At some subsequent time, the horns were moved to a position above and to the left of the front radiator fans on the long hood. With other UP locomotives, they acquired rooftop warning beacons about 1970. Some also received "We Can Handle It" slogans on the cab side in the early 1970s. HO Scale Model GP20s Mantua/Tyco An HO plastic GP20 body has been available with various drives from Mantua and Tyco since the early 1960s. The die work and level of detail on the body were very good for the time (in fact, one failing of Mantua in retrospect was that, once they switched to plastic models, their paint and finish didn't match the often excellent die work on the moldings of the locomotives and freight cars). The hood width on the GP20 body was also scale, unlike the contemporary Athearn GP7. The modeler must correct a few gaps and bulges in the cab sides and nose. The gaps in the pilots for the truck-mounted couplers must also be filled, or the step/pilot assemblies replaced with those from some other body shell. Finally, a dynamic brake blister and fan must be added from an Athearn GP7 shell. Prior to the release of the Proto 2000 model, the best option for modelers to build a GP20 was to find a Mantua/Tyco body at a swap meet and add a Hobbytown of Boston or Proto Power West chassis, as well as aftermarket details. The early Mantua/Tyco power truck was not satisfactory, and it's the chief reason it's so easy to find Mantua GP20 bodies at swap meets. The Mantua model was reissued in the 1990s with an 8-wheel drive chassis with flywheels; however, Mantua apparently persists in devaluing its investment in good die work by applying poor and unprototypical paint schemes. (A recent Mantua ad does list a UP paint scheme on the reissued model, but I haven't seen one.) The original GP20 was offered with UP paint, but the paint job was not up to more recent modelers' standards. However, an original model from the 1960s in good condition may have some collector interest. The reissued model, while reasonably priced, appears to be hard to obtain, and out of the box its detail isn't acceptable for a serious modeler. The Mantua body/new chassis strategy is still a good one for those who have the parts saved up, or who want to gain the operational improvement with a Proto Power West or Hobbytown chassis over a Proto 2000. However, the price of a Proto 2000 GP20 loco at discount will be comparable to the reissued Mantua model and well below the new chassis options. Proto 2000 Proto 2000 issued a GP20 model in late 1998. UP paint was offered on a second run of the model in early 1999. The models have the post-1962 numbers in the 470-499 series. The Proto 2000 is mid-range quality, with details like separate grab irons included with the model that must be added separately on competing brands. On the other hand, the details are often not well attached, and they sometimes fall off prior to packing the model in its box, or they fall off during removal from the box. Motor quality and flywheel "dwell time" are not as good as with Kato or Atlas models. The constant lighting circuit is the feature that has the effect of slowing the loco sufficiently to let it match speed with Kato or Atlas models; otherwise, they would run faster and match Athearn models' speed. The paint schemes are sharp and authentic, and once the modeler has reassembled the various parts that have fallen off the model, or written to Proto 2000 for the parts that didn't make it into the box, all that's necessary is assembly of the body and footboards to the chassis, replacement of the Kadee clones, and weathering to have an acceptable loco for the layout. Other Tenshodo Tenshodo offered a brass GP20 made in Japan in the early to mid 1960s. One version was painted and lettered for UP. The early Tenshodo brass diesels didn't run particularly well, but substitution of a Hobbytown chassis will result in a good-running unit. The UP paint and lettering on the model, based on catalog photos, does not appear to have been much more than an approximation. However, a model in good condition would be of collector interest. Overland Overland has offered collector-quality brass "Omaha GP20s". References Kamm, Al Jr. "Electro-Motive's GP20." Model Railroader, July, 1963, pp. 36-38. Strack, Don, and Dover, Dan. "Union Pacific All-time Roster, Part 3".Extra 2200 South Issue 69 (July-August-September 1979). Union Pacific Railroad. System Timetable No. 2. December 10, 1978.