HYDRA-MATIC TRANSMISSIONS 1953-1963

From the outset, the Hydra-Matic transmissions were built in a plant at Livonia, Michigan, under the Detroit Transmission Division. This Plant caught fire, August 14 1953, and as a consequence this interrupted production. Chevrolet Powerglides were fitted to US Pontiacs [already being fitted to Canadian Pontiacs], and Olds and Cadillacs were fitted with Buick Dynaflows. However, GM quickly leased an unused part of the huge plant owned by Kaiser at Willow Run, Michigan. This had been building Kaisers, Frazers and Henry J’s. Within a very short time, Hydra-Matic transmissions were in full production again. Kaiser then concentrated their production at their Toledo, Ohio, Plant, and as a consequence, GM acquired the whole building and expanded production to the whole building. It should be added that Canadian production was hardly affected, possibly because of the predominance of manual transmission cars and trucks, especially for export.
This is not the Willow Run auto assembly Plant, which was built right outside the transmission plant, a mere roadway separating the two buildings.
For 1961 Model Year, Detroit Transmission Division produced a new, "small Hydra-Matic" ostensibly for the Buick F-85, but on the back of series production, Willow Run produced a modified transmission for the Vauxhall PA series Cresta/ Velox: a three-speed torque converter ‘box. This might have been called the "61-05" transmission. This ‘box was also fitted by GM-Holden’s to locally-assembled PA’s.
A few months later, the same transmission was used in the Opel Kapitän, and also the Holden EK, as the "H-5-61" [launched May 1961]. This was replaced in later EK series by the 4-speed Model RHM-240-62-H, the Roto-Hydra-Matic, or "H-5-62". The Series EJ and EH were equipped with the "H-5-62" and later "HA-5-63" 4-speed units. Each unit was prefixed by the "H-5-61", etc., as a prefix stamped on the serial number plate attached to the casing., e.g. Holden’s service manual shows a plate for # H562-1012.
On October 1 1963, Detroit Transmission Division changed its name to the Hydra-Matic Division.