Turbo 350 History
After the release of the TH400, the TH350 became the little brother to it. Debuting in some 1969 Chevy cars, the TH350 has been a proven performer for many decades. The TH350 is strong, reliable and can be upgraded to be even more durable. It is common to see the TH350 at the track and in everything from a Nova, Chevelle or a hot street truck. With 3 forward gears and an aluminum case and a proven history of reliability on engines with moderate torque, it is a well established player. When it was introduced, the Turbo 350 replaced the 2 speed automatics of the day, like the Powerglide. The TH350 would eventually meet the same fate, this time to 4 speed overdrive transmissions. Though phased out in the later 1980's for 4 speed overdrive transmissions, it is still a popular transmission today. TH350's are relatively inexpensive to rebuild with a host of performance upgrades and stall converters available.
In 1979, TH350 transmissions began being built with lockup converters to combat reduced gas supplies, and subsequent rising fuel prices. TCC control units controlled the converter lockup. These transmissions can be identified by an electrical plug on the driver side of the transmission. Between the GM manufacturers, the bellhousing portion of the TH350 is the main difference. Chevy TH350 transmissions fit the SBC and BBC engines. Buick, Olds and Pontiac TH350 transmissions are usually interchangeable within each other's V8's.