Automatic Transmission

The General Motors TH350 is a widely regarded three-speed automatic transmission, introduced in 1969 as the successor to the Powerglide. Jointly developed by Chevy and Buick, it became known for its strength, versatility, and compact size, making it one of the shortest and strongest automatics suitable for Jeep conversions. This transmission features a 21-3/4" long, one-piece aluminum alloy case with an integral bellhousing and weighs approximately 120 lbs. It is identifiable by its distinctive oil pan, chamfered at the passenger side rear corner, and a vacuum modulator located at the right rear of the case. The TH350-C, introduced in late 1979, is a lockup torque converter version designed to improve fuel efficiency at cruising speeds, identifiable by an electrical plug on the left side of the transmission. The TH350 is natively compatible with Chevrolet 90-degree "Small Block" and "Big Block" patterned engines, including V6, V8, I6, and the Iron Duke I4. A separate Buick/Oldsmobile/Pontiac (BOP) version is compatible with Buick 90-degree V6 and V8 engines, and Oldsmobile and Pontiac 90-degree V8 engines. Dual-pattern "uni-cases" are available for compatibility with both Chevy and BOP engine blocks. The TH350 can also be adapted to a variety of AMC I6 & V8 engines with specific kits. Both 2WD and 4WD versions of the TH350 can be effectively used for conversions, with 2WD models featuring conical tailhousings that are typically replaced with a shorter 4WD output shaft. The HydraMatic 350 can be adapted to numerous Jeep and IH transfer cases, including the Dana 18, 20, and 300, as well as various New Process models. While factory GM 4WD applications with a TH350 often feature prohibitively long adapters and less desirable transfer cases for Jeep applications, aftermarket solutions are available.