When its favored supplier of steam locomotives introduced a 6,000-horsepower two-unit passenger diesel, Pennsy took notice. While EMD E7s had been in service on a short time, it took three of those units to equal the horsepower of two of Baldwin Locomotive Works' new DR-12-8-3000 model. In February, 1946, Pennsy ordered a pair of the DR-12-8-3000s, with an order for 22 more by October of that year. Mated in semi-permanently coupled pairs, the DR-12-8-3000s, or Centipedes, as they came to be known, were assigned to the carrier's flagship passenger trains, an assignment that lasted only a few years as reliability problems began to surface. Recognizing the complexities of the Centipedes' running gear and mechanical layout, PRR returned to Baldwin for more passenger units. But this time, the road specified a more common A1A-A1A truck arrangement.

In January, 1947, Pennsy ordered 18 DR-6-4-2000s in six 6,000-horsepower A-B-A sets, but instead of the "babyface" nose design of the Centipedes, Pennsy hired Raymond Loewy to design a new carbody style. Based on his styling of the carrier's T1 4-4-4-4 Duplex steamer, the sharknose diesel design was born. A year later, the styling was carried over to a freight version of the passenger shark. Between 1949 and 1952, Baldwin built 170 locomotives of the DR-4-4-1500 type and its successor, the RF-16 model, for the manufacturer's largest diesel customer, the Pennsylvania Railroad.

The addition of RT-624 center-cab transfer units to the PRR roster marked the beginning of the end for Baldwin. Although PRR placed 22 of the 2,400-horsepower double-engined units in service in 1951 and 1952, a single unit delivered in 1954 (as part of a 14-unit 1953 order) marked the end of an era, becoming the last Baldwin locomotives purchased by the PRR.

Softcover, 8.5" x 11", 72 pages, 171 photos