Sonnax Transmission Company is an industry leader in the cutting-edge design, manufacture and distribution of the highest quality products to the automotive aftermarket, commercial vehicle industries and industrial sectors utilizing drivetrain technology. Sonnax Transmission Company, a Marmon/Berkshire Hathaway company, serves the aftermarket with both the Rostra Powertrain Controls and Sonnax brands. After decades of serving the transmission aftermarket as standalone companies, Sonnax and Rostra Powertrain Controls integrated in 2021 to become a single, transmission-focused organization. What sets us apart from the competition is our passion for quality and innovation. This passion exhibits itself in our long-standing philosophy to address the root cause of a problem, and not just treat the symptoms. In striving to discover what causes common transmission and converter problems, we meld new ideas, materials and state-of-the-art testing to ensure our parts will restore OE performance, or make it better-than-new. Sonnax Transmission Company headquarters is in Bellows Falls, Vermont, with production facilities in Laurinburg, N.C. and technical development centers in California, Georgia, Indiana, Missouri and Wisconsin. We proudly hold ISO:9001 2015 certification for our Quality Management System.