Automatic Transmission

The GM TH400 is a legendary three-speed, automatic transmission known for its exceptional durability and versatility, making it a popular choice for various automotive applications and conversions. It is designed for longitudinal mounting and features a robust cast aluminum alloy case with a length of 24-3/8 inches. Conservatively rated at 450 ft-lbs of input torque, the TH400's capacity can be significantly increased with aftermarket building techniques, making it suitable for high-performance and heavy-duty use. Notable variations include the TH375, produced from 1972-1976 for smaller displacement cars, and the TH475, an extra-heavy-duty variant introduced in 1971 for larger trucks. The TH400 offers broad engine compatibility, natively fitting Chevrolet "Small Block" and "Big Block" patterned engines, as well as Buick, Oldsmobile, Pontiac, and Cadillac ("BOPC") engines. It can also be adapted for AMC I6 and V8 engines. It was originally introduced in 1964 and found its way into GM trucks and a wide range of vehicles across the automotive industry, including Jeeps, Jaguars, and more. This transmission is a highly sought-after component for conversions, particularly in Jeep applications, due to its adaptability with various transfer cases such as the Dana 18, 20, and 300, as well as New Process and NVG transfer cases. Both 2WD and 4WD versions can be utilized. Specific Jeep powertrains that originally featured the TH400 include various AMC models from 1965-1979 with different V8 and I6 engines.