The automatic gearbox THM250 is based on the THM350. This gearbox was released in 1974 and was applied in Chevrolet cars. The THM250 was developed and designed by GM as a part of Turbo Hydra-Matic family of automatic gearboxes. When taking into consideration the internal structure of the gearbox, the THM250 is very similar to THM350, apart from the intermediate clutch package with a band adjuster.