TH350 Transmission

The TH350 transmission is a three-speed automatic originally produced by General Motors beginning in 1969. Also referred to as the Turbo 350 transmission or 350 Turbo transmission, it was widely used in rear-wheel-drive GM cars and light trucks for several decades.

At Gearstar, each TH350 transmission for sale is built based on the intended application of the vehicle. This includes engine output, vehicle weight, gearing, tire size, and how the vehicle is expected to be used. The goal is to match the transmission configuration and torque converter to the overall drivetrain combination rather than applying a generic setup.

Why Choose a TH350 Transmission?

The TH350 is primarily used in classic and performance-oriented builds where a simple three-speed automatic is appropriate. Common applications include older GM muscle cars, street rods, and light trucks where compatibility with Chevrolet-based engines and straightforward serviceability are priorities.

There are a few reasons that the 350 Turbo transmission continues to be selected for these types of builds. Its compact size helps with fitment in older chassis where space can be limited. Its relatively simple hydraulic design eliminates the need for electronic controls, which can be an advantage in older or simplified vehicle electrical systems. It also benefits from long-term aftermarket support, with widely available service parts and upgrade components.

When properly configured and built with upgraded internal components, the TH350 can be used in higher torque applications, but its suitability depends on the overall vehicle weight, power level, and intended operating conditions.

What Makes a Gearstar TH350 Different?

Every turbo 350 transmission for sale from Gearstar begins with a complete teardown and inspection process. Transmission cases are thoroughly cleaned, media blasted, and carefully inspected for defects before assembly begins. This process allows our builders to identify any issues before the transmission is rebuilt and ensures every case receives a clean, durable finish.

Unlike mass-production rebuilders, at Gearstar one experienced builder assembles your transmission from start to finish. This approach allows for greater consistency, quality control, and customization throughout the build process.

Once the transmission is completed, we build and match a custom torque converter specifically for your application. The transmission and converter are then tested together on one of our in-house transmission dynos.

Custom TH350 Transmission Packages

Gearstar offers several TH350 transmission configurations to accommodate a wide range of horsepower levels and vehicle applications.

TH350 Level 2

Our Level 2 package is designed for mild street performance applications.

Key specifications include:

• Rated up to 400 horsepower

• Rated up to 375 lb-ft of torque

• Custom-built 12-inch high-performance torque converter

• Stall speed range of 1,600-2,200 RPM

• High-energy friction materials

• TransGo shift kit

• High-volume pump assembly

• Hardened intermediate race

• Super 36-element intermediate sprag

• External transmission cooler included

This package is an excellent choice for street-driven muscle cars, cruisers, and mild performance builds seeking improved durability and shift quality over a stock transmission.

TH350 Level 3

The Level 3 package is built for more aggressive street and street/strip combinations.

Key specifications include:

• Rated up to 500 horsepower

• Rated up to 475 lb-ft of torque

• Billet Yank Performance converter

• Stall speed range of 2,800-4,000 RPM

• Raybestos Stage 1 racing frictions

• Kevlar front band

• Heavy-duty low-reverse center support

• High-volume, high-flow pump assembly

• Super 36-element intermediate sprag

• Competition-calibrated TransGo shift system

This configuration is ideal for customers seeking increased holding power, firmer shifts, and improved durability under demanding performance conditions.

TH350 Level 4

The Level 4 package is our highest-performance 2WD TH350 transmission offering.

Key specifications include:

• Rated up to 700 horsepower

• Rated up to 550 lb-ft of torque

• 10-inch billet Yank Performance converter

• Stall speed range of 2,800-4,000 RPM

• 300M hardened input shaft and forward drum assembly

• Raybestos Stage 1 racing frictions

• Kevlar front band

• Heavy-duty center support upgrades

• High-volume, high-flow pump assembly

• Competition shift calibration options

For high-horsepower street cars and serious performance builds, the Level 4 package provides the strength needed to withstand substantial power while maintaining reliable operation.

TH350 4x4 Transmissions

For off-road and truck applications, Gearstar also offers dedicated Turbo 350 transmission packages for 4x4 vehicles.

Our 4x4 Level 3 package supports up to 500 horsepower and 475 lb-ft of torque, while the 4x4 Level 4 package is rated for up to 600 horsepower and 550 lb-ft of torque.

These transmissions incorporate many of the same performance upgrades found in our 2WD models while being configured specifically for four-wheel-drive applications.

Custom Torque Converter Matching

One of the most overlooked aspects of transmission performance is torque converter selection.

Many transmission suppliers use generic converters that may not properly match the engine, vehicle weight, gearing, or intended use. At Gearstar, every converter is custom-selected and built for the specific application.

By carefully matching stall speed and converter characteristics to the vehicle combination, we help maximize drivability, acceleration, efficiency, and overall performance.

Built for Your Combination

Every vehicle is different. A lightweight street rod requires a different transmission setup than a heavy truck. A mild small-block Chevrolet has different requirements than a high-horsepower big-block or stroker engine.

When ordering a TH350 transmission for sale from Gearstar, our team reviews critical vehicle information to ensure the transmission and converter package is tailored to your specific needs..

Frequently Asked Questions

Is a TH350 a 3 speed?

Yes. The TH350 transmission is a three-speed automatic transmission featuring gear ratios of 2.52:1 in first gear, 1.52:1 in second gear, and 1.00:1 in third gear.

Is a Turbo 350 and a TH350 the same?

Yes. The terms Turbo 350 transmission, 350 Turbo transmission, and TH350 all refer to the same General Motors three-speed automatic transmission.

What kind of transmission is in the Turbo 350?

The TH350 is a hydraulically controlled three-speed automatic transmission originally produced by General Motors. It is known for its compact size, durability, and widespread use in performance and restoration applications.

How much HP will a TH350 handle?

Horsepower capacity depends heavily on the quality of the build and the components used. Gearstar's TH350 packages range from 400 horsepower in Level 2 configurations up to 700 horsepower in Level 4 builds. Proper internal upgrades, converter selection, and calibration are critical to achieving reliable performance at higher power levels.

Is the turbo 350 a good transmission?

The Turbo 350 transmission is generally considered a solid, reliable three-speed automatic for applications where simplicity, compact size, and mechanical durability are priorities. Its effectiveness depends heavily on how it is built and matched to the engine, vehicle weight, gearing, and intended use.

Is a Turbo 400 better than a Turbo 350 transmission?

The Turbo 400 (TH400) and Turbo 350 (TH350) are designed for different use cases, rather than one being universally better than the other. The TH400 is a heavier-duty transmission with a stronger factory design and higher torque capacity, making it more commonly used in high-horsepower or heavy vehicle applications. The TH350 is lighter, more compact, and typically used where reduced weight, packaging constraints, or low to moderate power levels are a better fit. 

Get a Custom Quote for a TH350 Transmission

If you're looking for a TH350 transmission or a custom-built 350 turbo transmission package tailored to your vehicle, Gearstar can help.

Contact our team today to discuss your combination, performance goals, and vehicle specifications. We'll recommend the right TH350 package and build a transmission designed specifically for your application.