No one knows transmissions & torque converters like

Sonnax designs, develops and manufactures the highest quality aftermarket automotive products. We are the world’s largest full-line supplier of torque converter parts, and offer transmission and specialty driveline components through a global network of parts distributors.

Featured Products Where to Buy

View Sonnax Part Instructions

Enter a Sonnax part number below to view its instructions. For general reaming instructions, click here.

34200 40k web

4L80-E, 4L85-E

Smart-Tech® Overrun Clutch Valve Kit 34200-40K

Fits units '97-later.

T3 3 6081h

Roller Bearing Slip Yoke T3-3-6081H

Fits Powerglide, 350 and 350C. Also fits Saginaw 3- and 4-Speed, Muncie M20, M21 and M22 with 27-tooth spline. For use with roller bearing tail housing.

6l45 6l90 zip

6L45, 6L50, 6L80, 6L90

Zip Kit® 6L45-6L90-ZIP

Latest News

February 18, 2019

Important Change Coming to Sonnax Packaging

As part of an initiative to Go Green in ’19, Sonnax will cease including printed instructions with most products.

Beginning March 1, we will stop inserting instructions into the packaging of approximately 1,000 products. This change will primarily impact parts such as end plugs, valve kits and bushings that come in small bags. In general, instructions will continue to ship with larger components and boxed products such as Zip Kits® and The Sure Cure® kits.

Instructions for all products will remain available on the Sonnax website – and are now faster and easier to find.

Why is Sonnax doing this?

Reduce Waste: We printed more than 1 million pages of instructions last year— that’s a LOT of trees. 

Make the Sonnax Workplace Safer: The rising number of pages has been matched by more repetitive motion concerns and injuries among Sonnax employees packaging our smallest, bagged parts. Products packaged this way are also among the easiest to install. Instructions are often thrown away, unused.

To ensure everyone has quick access to all instructions, we created a simple online search tool: 

1. Quickly view instructions at

2. In the search box, enter the Sonnax part number found on the Sonnax packaging. 

If instructions are available, a PDF will open or your browser will download the file (your own browser settings control what happens). If no instructions are found, verify you are typing the correct part number or visit the part page on the website for product information.


Read More
January 23, 2019

Top Plow Truck Drivetrain Repairs & Upgrades

HEAVY SNOW. SUB-ZERO TEMPS. BLACK ICE. These are a few of old man winter’s favorite tricks…and they can lead to treacherous driving conditions. Working hard to keep roads safe, plow trucks often burn through transmissions, torque converters and driveshaft assemblies, and end up in the shop.

Check out these top-quality repairs and upgrades to get them back on the road and going strong before the next storm hits:

Read More
December 13, 2018

Sonnax Holiday Hours

From all of us at Sonnax, thank you for another amazing year! We truly appreciate your support, and look forward to working together again in 2019. 

Holiday Hours:

    Dec. 24: Closed
    Dec. 25: Closed
    Dec. 31: Closed
    Jan. 1: Closed

Happy holidays and best wishes for the New Year!

View News Archive

Upcoming Events

ATSG Technical Seminar

21850 Oxnard St., Woodland Hills, CA

March 30, 2019, 9:00AM - 4:00PM

Learn More

ATRA Technical Seminar

2020 E American Blvd., Bloomington, MN

April 13, 2019, 8:00AM - 4:00PM

Learn More

ATSG Technical Seminar

10220 Regency Circle, Omaha, NE

April 13, 2019, 9:00AM - 4:00PM

Learn More
See All Events

Sign up today for Sonnax enews!

You’ll be the first to know about:

  • New product releases
  • Free tech resources
  • News and events
  • Special updates

Select your topic(s) of interest and receive only the information that’s important to YOU.


Enjoy a rewarding career and relaxing quality of life
in beautiful Southern Vermont.

Recognized as one of the Best Places to Work in Vermont and recipient of the Governor's Worksite Wellness Award, Sonnax is a leading supplier to the automotive aftermarket. We design, manufacture, test and distribute a wide variety of innovative, high quality products used to remanufacture torque converters, rebuild automatic transmissions, upgrade driveshafts and protect the driveline from over-torque damage.

Sonnax is one of the fastest growing companies in the state of Vermont. Our name has become synonymous with exceptional service, cutting-edge designs, technical knowledge and customer dedication. Join an exciting front-line team focused on developing and delivering the best products in the industry, a team whose imagination, hard work and results are rewarded.

Careers at Sonnax