This comprehensive workshop service repair manual covers the International Harvester (IH) 1466, 1468, and 1486 tractor models, produced from the mid to late 1970s. These heavy-duty agricultural tractors were engineered for row-crop farming and general farm work, renowned for their powerful engines, robust construction, advanced hydraulics for their era, and versatile performance. Key selling points included their reliable DT-466 and DT-436 diesel engines, the 16-speed Power Shift transmission, and comfortable operator stations. The IH legacy is one of ruggedness and innovation, and these tractors represent a significant evolution in agricultural machinery, designed to enhance farming efficiency. This manual provides extensive information for service, repair, maintenance, and troubleshooting. It details engine overhaul procedures, drivetrain systems including the clutch and Power Shift transmission, hydraulic systems, and chassis components such as the front axle, steering, and brakes. Electrical systems, operator station features, and specific maintenance procedures like lubrication charts and fluid changes are also covered in depth. With over 1000 pages of content, this manual serves as an essential resource for owners, mechanics, and technicians, offering detailed disassembly, assembly, and diagnostic guidance to ensure the longevity and optimal performance of these classic International Harvester tractors.