Operating Era: 1923-1970. Atlantic Coast Line, Seaboard Coast Line. The U-5 was Atlantic Coast Line's first all steel "dry" phosphate hopper car. Three hundred cars of series 8175-8474 were built in 1923-26 and ran in revenue service until 1968. The cars had 8 roof hatches and 4 hoppers. The hopper doors were originally operated individually by chains wound around rods. These were replaced sometime in the late 1930's with collapsing rods that were connected together so that a single operation could open and close all doors. The cars were given AB brakes and a new lettering style in 1948. Lettering changed again the the 1950's. In the 1960's cars were shifted to locomotive sand service where they lasted into the late 1980's.