* Intended Use: Street driving, drag racing, off-roading, towing, etc., all require different characteristics.
* Power Level of the 350: A mildly modified engine will have different needs than a heavily built performance engine.
* Budget: Transmission options range widely in price.
Here are some common options and their suitability:
* TH350 (3-speed automatic): A very popular and robust choice for street applications. Relatively inexpensive to rebuild and parts are readily available. Good for mild to moderately powerful engines. Simple and reliable. Not ideal for high-performance applications or towing heavy loads.
* TH400 (3-speed automatic): Stronger and more durable than the TH350, especially for high-torque applications. Excellent for towing and high-horsepower engines. Less fuel-efficient than the TH350.
* 700R4/4L60E (4-speed automatic): Offers overdrive for improved fuel economy on the highway. A good compromise between performance and fuel efficiency. The 4L60E is the electronically controlled version and is found in many later model vehicles. The 700R4 is more common in older builds. Can be less robust than the TH400 depending on modifications and build.
* Powerglide (2-speed automatic): A very simple and lightweight automatic, primarily used in drag racing applications. Not suitable for street use or towing.
* SM465 (4-speed manual): A very strong and reliable manual transmission, often used in trucks and off-road vehicles. Not ideal for street performance due to a tall 1st gear.
* T5 (5-speed manual): A common and relatively lightweight 5-speed manual transmission, often found in GM vehicles. Good for street performance and offers better fuel economy than a 4-speed. Various versions exist with differing gear ratios.
* Tremec T56 (6-speed manual): High-performance 6-speed manual transmission, commonly used in muscle cars and performance vehicles. Offers close-ratio gears and high strength. More expensive.
In short:
* For a mild-mannered street car: TH350 or 700R4/4L60E are great choices.
* For a high-performance street car or drag racing: TH400 or a Tremec T56 (manual).
* For towing: TH400 or a heavy-duty 4L60E/4L80E (the 4L80E is a heavier-duty version of the 4L60E).
* For off-roading: SM465 or a heavy-duty automatic.
Before making a decision, consider the specific details of your 350 build and its intended use. Consulting with a transmission specialist is always a good idea.
