TH350 / TH350C Transmission Rebuild Kit – Heavy Duty Stage 4 Master Kit

This Stage 4 Heavy Duty Line Master Rebuild Kit is our top-tier solution for GM TH350 & TH350C automatic transmissions (1969–1986 Chevrolet, GMC, Pontiac, Oldsmobile, Buick, and more). Engineered for maximum durability and performance, this kit is trusted by professional builders for towing, racing, and classic restorations.
 
🔧 Kit Includes:
Alto High Energy Graphite (HEG) Friction Module – Extreme durability under load and heat
Alto Hardened Steel Plate Module – Precision-machined, USA-made hardened steels
Alto Full Gasket Set – “Full Ring” design ensures superior sealing
Alto Red Eagle or Kevlar Front Band – Both heavy-duty, long-life upgrades (band type depends on stock)
Red Stripe Modulator – Crisp, adjustable shifts
Alto Nylon Filter – Enhanced flow and filtration
Alto Bushing Kit – Complete coverage, OEM fit
Alto Washer Kit – Full thrust washer set (not partial)
 
💡 Why Our Kits Stand Out
Many rebuild kits sold by bulk resellers are assembled using white-label import steels and mixed-brand friction modules. That means you might get one clutch from Alto, another from Raybestos, another from Exedy, and others completely unbranded  whatever was cheapest at the time. The other issues you’ll see from large resellers are the use of soft steels and white-label, no-name vacuum-board components sourced from overseas. These are often low-grade RB-rated steels at best, which will create uneven wear, shorter lifespan, and unpredictable performance.
Our kits are different. Every component is inclusive and matched:
Alto High Energy Graphite (HEG) Frictions (USA-made)
Alto Hardened Steels (USA-made)
Alto gaskets, bushings, washers, and filter (USA-made)
You know exactly what you’re getting — consistent, proven components from the brand trusted by professional builders for over 40 years.
 
💡 Why Choose This Kit:
Complete Alto Components – Matched and quality-verified
True Master Kit – No filler, no mystery parts, no stock leftovers
Professional Grade – The same components we install in our in-house builds
USA Seller – Over 40 years of transmission rebuilding expertise, fast shipping, and dependable support
 
📦 Shipping Info:
Free Shipping to the Lower 48 U.S. States
Same-Day Shipping on 95% of orders
AK, HI, PR, APO – Contact us for custom shipping options
International Buyers – Eligible through the eBay Global Shipping Program
 
🛑 Build With Confidence
No corners cut. No cheap imports. No surprises.
⚡ Heavy Duty Alto Components – USA-made quality trusted by pros.
👉 Order once. Build it right the first time.
 
🔴 Alto High Energy Graphite (HEG) Frictions
Composition: Non-asbestos organic friction material with graphitic additives to improve lubricity and thermal stability.
Performance: Designed for consistent performance and reliable engagement under sustained heat and load. Ideal for general high-energy applications where smooth apply and long wear life are required.
Applications: Automatic transmissions in passenger cars, trucks, towing applications, and classic restorations.
Friction Data:
Dynamic coefficient (μd): ~0.119–0.132
Static coefficient (μss): ~0.138–0.147
Durability: Tested at high cycle counts with an energy density of 350 ft-lbs/in², showing controlled wear and stable performance
Friction Datasheets original.
Rating: High Energy Material — proven for reliable service life in daily drivers, towing, and performance builds up to moderate horsepower ranges.
 
⚙️ Alto RC90® Steels (OEM-Grade Performance Steels)
Process: Heat-treated and Rockwell-tested steels manufactured to RC90 hardness for strength and durability.
Benefits:
RC90 hardness ensures long wear life and resistance to distortion
Provides smooth, consistent engagement with HEG frictions
Balanced durability without the extra cost of Kolene treatment
Applications: Used with HEG frictions in rebuilds for stock, towing, and performance applications where reliable service life is required.
Industry Reputation: A trusted OEM-grade performance steel, widely used in professional rebuilds for its balance of cost, reliability, and wear resistance.