UD Trucks Corporation (UDトラックス株式会社, UD Torakkusu Kabushikigaisha) is a Japanese company whose principal business is the manufacturing and sales of diesel trucks, buses, bus chassis and special-purpose vehicles. Its headquarters are located in Ageo, Saitama, Japan. The company is a wholly owned subsidiary of Isuzu since 2021. Until 2010, the company was known as Nissan Diesel. The UD name was originally used for the company's Uniflow Diesel Engine (a two-stroke diesel engine), developed in 1955, but is now marketed as meaning "Ultimate Dependability". History 1935–1949 In December 1935, Nihon Diesel Industries, Ltd, in Kawaguchi, Japan on the outskirts of Tokyo was established under the leadership of Kenzo Adachi, where he purchased diesel engine schematics from a Krupp-Junkers patent. The company started production of KD-series 2-cycle diesel engines after entering into partnership and technology exchange with Friedrich Krupp AG. In November 1939, to test the durability of the LD1 truck, the company went on a test drive across Japan. The drive went to the villages of Hakone, Osaka, Kyoto, Gero, Ikaho, Niigata and Aizu before returning to Kawaguchi. The route was on very primitive mountain roads and very rural conditions. The truck returned 13 days later on November 20 without incurring any failure, and soon the trucks reliability became known. In 1940 production of 4.5-ton-payload TT6 series trucks started, and in 1942 the company was now known as Kanega-Fuchi Diesel Co., Ltd. In development of 7.5-ton-payload TN93 series trucks, featuring the largest payload capacity in the Japanese market, and the nation's first monocoque-type BR3 series buses with rear-mounted engines. In 1946 the company name changed to Minsei Industries, Ltd. In 1949 development of 7.5-ton-payload TN93 series trucks started. 1950–1959 In 1950 Minsei Diesel Industries, Ltd. was spun off from Minsei Industries; and the company was on the way to becoming a comprehensive transport equipment manufacturer. In 1955 the UD name was born, when Minsei Diesel Industries introduced a range uniflow-scavenging 2-cycle diesel engine. Of course, the UD stood for "Uniflow Diesel", named after the engine they had invented for use in their trucks. The production of various trucks and buses with 81 kW (110 PS) UD3, 110 kW (150 PS) UD4 and 169 kW (230 PS) UD6 engines began. In 1957 the development of Japan's first RFA series air-suspension buses and 10-ton-payload 6TW10 series trucks called "Jumbo" in overseas markets began. 1960–1969 In 1960, Nissan Motor Co., Ltd. acquired Minsei Diesel,