to extensively electrify its primary lines. The DD1 electric locomotives were developed from the prototypes that were tested on LIRR trackage. Later it saw power such as the B3. The LIRR's steam passenger locomotives were modernized from 1901 to 1906, and by 1927, it was the first Class I railroad to replace all its wood passenger cars with steel. In 1926, the LIRR was the first U.S. railroad to begin using diesel locomotives. The last steam locomotive was a G5s operated until 1955. Electric storage battery cars were used on the West Hempstead Branch (Valley Stream to Mineola) from 1913 until it was electrified in 1926, and on the Bushwick Branch prior to the end of its passenger operations in 1924. The Central Branch from Garden City east to Mitchel Field was electrified with third rail in 1915, but used ex-Ocean Electric Railway trolley cars until 1933. Normal electric trains, such as the MP41 were then used until 1950, when they were replaced by MP54's until the line's abandonment in 1953. One of the most popular decisions by Governor Nelson A. Rockefeller after the 1966 takeover was replacing the entire electric passenger fleet with M1 cars. It acquired 770 M1 cars built by Budd and General Electric from 1968 to 1974, and 174 M3 cars, built in 1985 and 1986, also by the Budd Company. Diesel-hauled trains through the late 1990s were operated using 1950s-era P72/PT75 series coaches built by Pullman-Standard. One end of the train was often powered by 28 EMD GP38-2 and 23 MP15AC diesel-electric locomotives, pulling a total of about 223 passenger cars, mostly former electric multiple units. For the other end of the train, the LIRR used a number of older locomotives converted to "power packs", in which the original prime movers were replaced with engines/generators solely for supplying HEP (head-end power for the lights and heating) with the engineer's control stand left intact. Locomotives converted included Alco FA-1s and FA-2s, EMD F7s, and one F9. One individual power pack was further converted into a power car for the C1 bilevel cars in the 1990s. The power packs were later sold to other operators, preserved in museums, or scrapped. In 1997 and 1998, the LIRR received 134 double-decker C3 passenger cars from Kawasaki, including 23 cab control cars, and 46 General Motors Electro-Motive Division diesel-electric locomotives (23 diesel DE30ACs and 23 dual-mode DM30ACs) to pull them,