As Norton said, the 2955 number stamped on the frame was used for tank cars beginning with the prewar 2955 and 2755 tank car, then the postwar 2755s, 2555s, 2855s, & 6555s. Someone else may correct me if wrong, but I believe only the 2755s, 2555s, & 6555s can be found in silver. Starting 1946, Lionel modified the frame even though it retained the 2955 number. Up through 1945 the frame had had openings on the ends in the frame under the ends of the tanks, but in 1946 and later, those openings were filled making more of a deck underneath the ends of the tank. Previous to 1946, the silver 2755s had steps on the corners. Those steps were eliminated on 2555s during the 1946 production year. Early 2555s can be found with steps. Cars that have been refinished are often done to the taste of the one doing the refinishing without regard to original configuration.
Dan
