Baldwin designed the DR-6-4-1500 as a dual service locomotive to compete with EMD's F-3 and Alco's FA-1, but with the added advantage of being easy on light rail branch lines by virtue of its GSC Commonwealth A-1-A trucks. It was powered by the 8-cylinder turbocharged model 608SC diesel prime mover, and in comparison to the freight only DR-4-4-1500, it was slightly longer, 61 feet for the DR-6-4-1500, versus 55 feet 6 inches for the DR-4-4-1500. Only nine DR-6-4-1500's were built, seven cab units and two boosters. The SAL owned three cab units, all retired in 1964.