The International Harvester 1066 tractor, produced from 1971 to 1976, represents a significant achievement in agricultural machinery. As part of the renowned 'Hydro 70' and 'Dyna-Torq' series, this robust machine is powered by a 6-cylinder, 466 cubic inch (7.6-liter) International Harvester DT-466 diesel engine, delivering approximately 100-120 horsepower and substantial torque for demanding tasks. Known for its power, reliability, and versatility, the 1066 was a cornerstone of farming operations, offering a 10-speed Power Shift or 16-speed Synchro-Range transmission, with standard 2WD and available 4WD configurations. Its enduring reputation stems from International Harvester's legacy as a prominent manufacturer, with the 1066 being a testament to their engineering quality and commitment to agricultural productivity. This comprehensive Workshop Service Manual (WSM) provides in-depth service and repair information for the International Harvester 1066 tractor. It covers all essential systems, including the engine, drivetrain, hydraulics, and electrical components, detailing everything from routine maintenance procedures and lubrication schedules to complex overhaul and repair instructions. The manual is designed to empower owners and technicians by offering step-by-step guidance, diagnostic flowcharts, and detailed troubleshooting sections, all supported by illustrations and wiring diagrams. Its purpose is to facilitate efficient maintenance and repair, enabling users to perform necessary work themselves, thereby increasing their knowledge and independence while potentially saving on professional service costs.