Chevy TH350 Turbo Hydra-Matic Transmission for Sale | OEM 3-Speed Automatic

Description

Transmission Background

The GM Turbo Hydra-Matic 350, universally known as the TH350 or Turbo 350, is the most widely produced automatic transmission in General Motors history. Introduced in 1969 as a 3-speed replacement for the two-speed Powerglide, it appeared in virtually every rear-wheel-drive GM passenger car and light truck from 1969 through 1986. Chevrolet, Pontiac, Oldsmobile, Buick, GMC, and Cadillac all ran the TH350 in some form across that seventeen-year window. It motivated Camaros, Novas, Chevelles, Malibus, Monte Carlos, Corvettes, Firebirds, Grand Prixs, Cutlass Supremes, and virtually every GM rear-drive truck and van of the era.

The TH350 was developed jointly by Chevrolet and Buick (giving it the internal CBC350 designation, Chevrolet-Buick Combined) and was manufactured at multiple GM facilities in Flint, Michigan, Toledo, Ohio, and Windsor, Ontario. The one-piece aluminum alloy case measures just 21.75 inches long, significantly shorter than the TH400, and weighs only 120 lbs. That combination of compact dimensions and light weight made it the transmission of choice for GM’s small-block V8 applications where size and weight mattered. The TH400 was reserved for big-block applications where the extra torque capacity justified its larger envelope.

Decades after production ended, the TH350 remains one of the most popular transmissions for classic car restoration, restomod builds, and engine swap projects. Its fully hydraulic control system (no electronics to fail), straightforward valve body, and enormous aftermarket support make it the default automatic for anyone building a classic GM vehicle on a budget. Novak Conversions, the specialists in Jeep drivetrain conversions, specifically call out the TH350 as the shortest and one of the strongest automatics adaptable into a Jeep.

When Replacement Becomes Necessary

• Slipping between gears, generally clutch pack wear or low line pressure from valve body or pump wear
• No 2nd gear or no 3rd gear, pointing to band or clutch pack failure inside the transmission
• Transmission will not engage from park, usually a linkage adjustment issue or manual valve problem in the valve body
• Fluid leak at the pan gasket or tailshaft seal, common on aged TH350s with original rubber seals
• Hard or delayed shift from 1st to 2nd, typically vacuum modulator failure (the modulator is the primary shift-timing control on the TH350)
• Lockup converter failing to engage or release on TH350-C units, traced to lockup solenoid or electrical feed problems

Known Weak Points

• Chevy versus BOP bellhousing incompatibility, the most common TH350 sourcing error: the TH350 came with either the Chevrolet bellhousing pattern (for SBC, BBC, and GM inline engines) or the BOP bellhousing pattern (for Buick, Oldsmobile, and Pontiac engines). A Chevy-pattern TH350 will not bolt to a Pontiac, Olds, or Buick engine without changing the bellhousing pattern. We confirm bellhousing pattern on every order.
• TH350 versus TH350-C compatibility: the standard TH350 and the TH350-C use different pumps, input shafts, and torque converters that are NOT interchangeable. The TH350-C can be identified by an electrical connector on the driver’s side of the case. We document lockup versus non-lockup on every order.
• End play issue, the TH350’s known weak point: there is excessive end play between the fluid pump and center support that lets the direct clutch drum wobble slightly. This causes accelerated wear on the drum bushing and pump. The fix during rebuild is simple: install a thrust washer between the forward clutch drum and primary planetary gear, and replace the drum bushing with a thicker unit. We note any obvious drum wobble or pump noise before shipment.
• Vacuum modulator wear: the vacuum modulator controls shift timing. A ruptured modulator (which allows transmission fluid into the intake manifold) causes harsh or erratic shifts. We inspect for modulator integrity and leakage before shipment.
• Tailshaft length must match application: the 6-inch tailshaft is correct for most passenger cars. The 9-inch is standard for square-body trucks and Suburbans. Using the wrong tailshaft length puts the driveshaft yoke in the wrong position. We confirm tailshaft length on every order.

TH350 Key Variants and Bellhousing Patterns

Critical buyer information for ordering the correct TH350:

What Ships and What Does Not

Direct-Fit Vehicle Applications

The TH350 was factory installed in virtually every rear-wheel-drive GM passenger car and light truck from 1969 to 1986:

For Jeep and other adapter conversions, Novak Conversions specifically recommends the TH350 as one of the shortest and strongest automatic options adaptable into a Jeep CJ, Wrangler, or similar chassis. Call us with your specific build plan.

Not sure if this fits? Call us. We verify fitment before every order ships.

Search Terms Buyers Use

Chevy TH350 | Turbo 350 transmission | TH350 for sale | Turbo Hydra-Matic 350 | TH350-C lockup | GM 3-speed automatic | Chevy 350 transmission | TH350 BOP | TH350 Chevy pattern | CBC350 transmission

Used OEM Versus Professional Rebuild

For a classic Chevelle, Camaro, Nova, Monte Carlo, or square-body truck build on a budget, a documented used TH350 with bellhousing verified and gears cycled is the cost-effective path. For a performance build or a vehicle that will see heavy use, a professional rebuild with a shift kit (TransGo or B&M), upgraded clutches, and the end-play correction is the better investment. Rebuilt TH350s with performance shift kits typically run $1,200 to $2,200 from established GM transmission shops, plus the torque converter.

Inspection Workflow

• Test stand cycling through all 3 forward gears and reverse with shift quality logged
• Bellhousing pattern verified: Chevrolet (peak at top center) or BOP (valley at top center)
• Tailshaft length measured and documented (6, 9, or 12 inch)
• TH350 versus TH350-C lockup status confirmed via case identification
• Vacuum modulator inspected for leakage or rupture
• External seal and gasket inspection at pan, tailshaft, and pump
• Direct clutch drum wobble or pump noise checked, the TH350’s known weak point

Pre-Purchase Buyer Notes

• Verify your engine’s bellhousing pattern first: a Chevy small-block, big-block, or GM inline engine takes the Chevrolet pattern. A Buick, Olds, Pontiac, or most Cadillac V8 takes the BOP pattern. Match this before anything else.
• Match the tailshaft length to your driveshaft setup: 6-inch tailshafts are most passenger car applications, 9-inch is square-body truck standard, 12-inch is less common. Wrong length puts the driveshaft yoke out of position.
• TH350 versus TH350-C is not interchangeable without parts changes: pumps, input shafts, and torque converters are different. If your build uses lockup converter control, source a TH350-C specifically. If it does not, the simpler standard TH350 is the cleaner choice.
• Plan a shift kit at install: TransGo and B&M produce shift kits that firm up the shifts, extend clutch life under performance use, and run inexpensively. Worth the investment during install.
• Address the end-play issue at rebuild: if you are rebuilding the unit, install the thrust washer between forward clutch drum and primary planetary, and upgrade the drum bushing. Cheap parts, big reliability win.

Why Buy From Part Nests

• Bellhousing pattern verified: Chevrolet or BOP pattern documented before payment
• Tailshaft length confirmed: 6, 9, or 12 inch noted on every order
• TH350 versus TH350-C lockup status identified up front
• All 3 forward gears and reverse cycled on the test stand before shipment
• Vacuum modulator integrity checked
• No core return required
• Free freight pallet delivery to every state
• 15 day replacement warranty against internal defects
• Call us to speak with someone who knows TH350 bellhousing compatibility, tailshaft applications, and the difference between standard and lockup converter variants

Additional Reference