The SD38 quickly became Conrail's favorite for hump and yard duty at locations such as Stanley Yard in Toledo, OH, Allentown (PA) yard, Oak Island Yard in Newark, NJ and Elkhart, IN.. The fleet of 35 units (nearly half of all SD38's built, with Conrail now owning the most) were inherited from the Penn Central and were typically paired with MT4 and MT6 slugs. Conrail 6925 through 6959 was built in May of 1970. The non-turbocharged locomotives were capable of 2,000hp and carried a 4,000 gallon fuel tank.

In 1999, the fleet was divided between Norfolk Southern and CSX. Those assigned to NS were renumbered into the 3800-3820 series, while CSX allocated units became 2455-2467.