Part of the EMD Dash 2 line, the SD45-2 was an upgraded SD45. Like the SD45, the SD45-2 had an EMD 645E3 20-cylinder engine producing 3,600 horsepower (2,680 kW). The main spotting difference between an SD45 and an SD45-2 was the long hood and the rear radiator. On the SD45 the long hood is flared whereas on the SD45-2 it is vertical and the rear cooling fans are more spread out on the top of the rear of the long hood. This unit used the same frame as the EMD SD40-2 and EMD SD38-2. The largest owner of the SD45-2 was the Atchison, Topeka, & Santa Fe with 90 units, the Clinchfield had 18 units, Seaboard Coast line had 15 units and Erie Lackawanna rostered 13 units.
A few cabless SD45-2Bs were built by Santa Fe from units undergoing remanufacturing. In all but one case (5510), the dynamic brakes were moved to the opposite end of the hood from the radiators; they were originally near the center of the hood. With no cab, these B-units are controlled from other locomotives.
In September 2015, Norfolk Southern revealed its SD45-2 numbered 1700 painted back to its Erie Lackawanna color scheme at Chattanooga, Tennessee. This is the second unit from an NS predecessor painted back into its original colors.