Introduced in 1964, the TH400 is an automatic shift, three-speed, longitudinally positioned transmission. It is highly regarded for its supreme durability. This model has a conservative rate of 450 ft. lbs of input torque, though that can be easily upgraded with aftermarket improvements. Monster These transmissions can come up to a maximum of 1000 torque. The TH400 transmission has available a variety of performance ratings, such as mild, heavy-duty, supersport, and SS Xtreme. The higher model that is chosen, the higher rated the horsepower and torque will be.