The B platform (also known as the B body) is a full-size rear-wheel drive car platform that was produced by General Motors (GM) from 1926 to 1996. Originally made for Oldsmobile and Buick, all of General Motors's five main makes would use it at some point. It was closely related to the original rear-wheel drive C and D platforms, and was used for convertibles, hardtops, coupes, sedans, and station wagons. With approximately 12,960,000 units built, divided across four marques, the 1965-70 B platform is the fourth best selling automobile platform in history after the Volkswagen Beetle, Ford Model T and the Fiat 124. Originally, the B platform was used for Buick and Oldsmobile products, with the A platform for Chevrolet and Oakland, and the C and D platforms devoted to Cadillac. During the General Motors companion make program, Vikings and Marquettes were also manufactured on this platform, as were La Salles from 1936 to 1940. The B platform became GM's base model platform in 1958, when all existing Chevrolet products were upgraded to the B platform. The B platform was used for the Pontiac Streamliner Torpedo and Streamliner, the Oldsmobile L-Series, Series 70 and Series 88, the Buick Special and Century, the LaSalle Series 50 and the Cadillac Series 60, Series 61 and Series 63. For the 1959 model year, the previous A and B bodies were built on the new B platform that lasted until 1996. During this period, the B was the most modest of GM's three full-sized platforms, slotting below the upscale C and the luxury D. The A platform designation would be resurrected by GM in 1964 for a new series of intermediate-sized cars including the Chevrolet Chevelle, Pontiac Tempest, Oldsmobile Cutlass and Buick Skylark. History The GM B platform was introduced in 1926 with the Buick Master Six, and the Oldsmobile Model 30, and had at least 12 major re-engineering and restyling efforts, in 1937, 1939, 1941, 1949, 1954, 1957, 1959, 1961, 1965, 1971, 1977, and 1991; along with interim styling changes in 1942, 1969 and 1980 that included new sheetmetal and revised rooflines. The platform was downsized in length by approximately 10 inches in 1977 and reduced in weight by an average of 800 pounds. In 1991, the platform received its last major redesign, regaining several inches in length, numerous frame improvements and reinforcements, while the shorter wheelbase remained unchanged. The last B-cars rolled