The Gen 1 Eaton AutoShift Transmission Control Unit (TCU) is a foundational component in early automated manual transmission systems, responsible for managing gear shifts, clutch operation, and communication with engine sensors. Designed to improve drivability and reduce driver workload, this TCU delivers consistent performance and fuel efficiency in heavy-duty commercial vehicles. As a legacy system, the Gen 1 TCU remains a critical part for fleets still operating older Eaton AutoShift-equipped trucks. Weller Truck Parts offers quality-tested used OEM Gen 1 Eaton AutoShift TCUs that provide a cost-effective solution for maintaining legacy systems. Each unit is inspected and verified for functionality to ensure dependable performance. Backed by Weller’s industry-leading warranty and supported by expert tech support and responsive customer service, you can count on Weller to help keep your fleet moving. Whether you're replacing a failed module or extending the life of your existing equipment, Weller delivers trusted parts with unmatched support.