EMD offered revised variants of the GP38, GP39 and GP40 in the “Dash-2” series of road switchers from 1972 onwards. Basically nothing changed in the power train, so that the GP38-2 had a V16 without turbocharger with 2,000 hp, the GP39-2 a V12 with 2,300 hp and the GP40-2 a V16 with 3,000 hp. The main innovation was a modular electronic equipment that allowed easier maintenance and originated from the DDA40X. Improvements to the power train concerned efficiency and reliability.

The GP38-2 was the most successful model with a total of 2,213 units sold. Of these, 1,799 remained in the United States, where the Missouri Pacific, Penn Central and Southern each bought more than 200 units. 156 machines were exported to Mexico and one to Saudi Arabia. 257 copies were built in Canada by GMD and accepted by Canadian customers. 51 of these were built for the Canadian National with the wider “comfort cab”. The latter are referred to as the GP38-2W by railway fans to distinguish them, although the manufacturer never uses this designation. Thanks to its simplified design, the engine achieves such a high degree of reliability that in 2020 most GP38-2s were still in use.

The GP40-2 was also available from 1972 and, with a total of 1,143 units, produced a slightly smaller number than the GP40. The largest customer in the USA was Baltimore and Ohio, which bought 218 units. Three GP40P-2s were built for the Southern Pacific, which were intended for use in front of passenger trains. 44 locomotives were exported to Mexico. 279 pieces were built in Canada, all of which stayed in the country. By far the largest part of this was the Canadian National with 268 pieces. Over the years many aging GP40-2s have had their turbochargers removed to improve reliability and henceforth continued to exist as GP38-2.

While the GP39, with its poorer reliability compared to the GP38, did not become an economic success, EMD was able to sell larger numbers of the improved GP39-2. From a total of 239 produced copies, the ATSF took 106 pieces, which were completed by 40 others from the Burlington Northern after the merger to BNSF. Also included in the GP39-2 are some converted GP40-2s that have been given electric train heating. Since a significant part of the engine power is no longer available for traction, they were designated as GP39H-2.