The Turbo Hydra-matic 350 was first used in 1969 model cars. It was developed jointly by Buick and Chevrolet to replace the two-speed Super Turbine 300 and aluminium-case Powerglide transmissions. So, although it carries the Turbo Hydra-matic name, the Hydra-matic Division of General Motors had little, if anything, to do with its design. The 350 and its 250, 250c, 350c and 375b derivatives have been manufactured by Buick in its Flint, Michigan, plant and by Chevrolet in Toledo and Parma, Ohio, and Windsor, Ontario. Some would suggest that the THM350 (or Turbo 350 as called by drag racers and car enthusiasts) was based on the earlier Buick Super Turbine 300 (some components interchange between the two) Both Chevrolet and Buick divisions produced the THM350.