The SC and the SW were built simultaneously at EMC, though EMC was pushing the SW which had a fabricated welded frame ("W" for welded and "C" for cast). The SC had a cast frame which EMC could not produce in its own shop, hence the attempt to sell the SW over the SC. Though there has been some confusion between the two models in the past, close-up photographs have revealed that the MoPac units were indeed SC's with cast frames (road numbers 9000-9003). When welded frames began in late 1936, many railroad people viewed them as a cheap imitation for a substantial cast frame. Consequently, engineers at La Grange decided to disguise their welded frames by applying a fake sheet metal section at each corner of the frame. These appeared on the SW1's, NW2's and TR2's until April 1949, when a cost cutting measure struck them from the package.By this time no one cared about whether frames were welded or cast. In 1938 MoPac subsidiary Union Terminal Railway (UT) got into the diesel act by purchasing an SW from EMC, which was outshopped as UT-5. In December the Saint Joseph Belt (SJB) picked up an SW (SJB-10).

In the roster section of the book, the following is shown for the SW's: UT-5 became SJB-5, then MP 6005, built 05/38 (c/n 718), retired 8/65, to PNC, to Pickens, renumbered PIRR-3. UT-10 is shown at becoming SJB-10, then MP 6006, built 12/38 (c/n 751) retired 9/63, scrapped. So by process of elimination, the locomotive shown MAY have been MP 6006, built as either SJB-10 or UT-10.

This photo was taken across the IHB main line from EMD, this locomotive is awaiting its date with Pielet Brothers Scrap Metal. This is not the appearance it had when it left Baldwin. The SAL purchased three cab units (#'s 2700-2702) known by the nickname "Babyface", and placed this unit in service November 23, 1947 at Tampa, Florida. Numbers 2701-2702 were placed in service January 1948 at Hamlet, North Carolina. When delivered, the nose door was flush with the cab front, no MU was visible, and the headlight was a single bulb with a refector. The only other railroad to purchase this model was the NYC, and those units had different style numberboards and a cast pilot with retractable couplers. Within a year of delivery, the NYC changed out the trucks in an attempt to improve riding qualities. The NYC units were stored by 1958, in spite of re-powering with EMD 567's in 1955, and off the roster by 1960. The SAL units operated mostly on secondary runs in Florida, lasting 17 years until traded to EMD for SDP35's in 1964.

Only nine of this model were built, four A units and two B units for the NYC, and three A units for SAL. The SAL units remained essentially unchanged (except for headlight, front door, and MU connections), but the NYC replaced the GSC Commonwealth trucks with drop equalizer trucks in attempt to minimize the rough ride, and in the process, had to shorten the fuel tanks to accommodate the truck change. During the mid-1950's, the NYC sent all their DR-6-4-1500's to EMD and replaced the Baldwin 608SC prime movers with 567's, retaining the Westinghouse electrical gear, but replacing Baldwin's electro-pneumatic throttle and MU equipment with EMD's. Even that was not good enough, the NYC units were stored by 1958, and off the roster by December 1960. Behind 2700 in this photo are some B&O Sharknoses, and all are awaiting scrapping, traded to EMD for new power.

Baldwin built only seven cab and two booster units of this model. In February 1946, the NYC ordered two A-B-A sets, and SAL ordered three cab units (#'s 2700-2702), for a total production of nine units in seven months. The NYC introduced their units in service November 22, 1947, and the SAL placed their first unit number 2700 in service the next day. The SAL units spent their service life mostly on secondary runs in Florida, and after 17 years of service, were traded to EMD. Although the NYC re-powered their copies with EMD 567's, the SAL retained their original Baldwin 608SC diesels to the end. The SAL did modify the headlight, the door below the headlight, and added MU to the nose. The numberboards on the SAL units were a Baldwin design, although the NYC versions were more like EMD FT numberboards. The model designation DR-6-4-1500 translates to: Diesel Road, 6 axles, 4 traction motors, 1500 horsepower.

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.