The International Harvester 986 Tractor, produced from 1976 to 1979, represents a significant piece of agricultural machinery known for its robust build and reliable performance. Powered by a D-358 naturally aspirated, 6-cylinder diesel engine, this tractor delivered approximately 98 PTO horsepower, making it a capable workhorse for various farming and operational tasks. Its engineering quality is reflected in its sturdy construction, including a Duplex Synchromesh gearbox and a standard 540/1000 RPM PTO, with an optional Power Shift Transmission available. The 986 was designed with operator efficiency in mind, featuring hydraulic power steering and an ergonomically designed operator station. Its industry impact is recognized for its strong performance within its horsepower class, solidifying its reputation as a dependable tractor. This comprehensive Workshop Service Manual (WSM) is designed to provide in-depth service and repair information for the International Harvester 986 Tractor. It covers all essential areas, including detailed overhaul and diagnostics for the engine, transmission, hydraulics, and electrical systems, along with specific guidance on steering, brakes, chassis, and body components. The manual offers step-by-step repair instructions, disassembly and assembly procedures, and adjustment guidelines, supported by clear illustrations and wiring diagrams to aid in troubleshooting. Routine maintenance schedules, fluid specifications, and common wear item identification are also included, empowering tractor owners, mechanics, and DIY enthusiasts to effectively maintain and repair their equipment, ultimately saving costs and ensuring optimal performance.