This Workshop Service Repair Manual covers the Nuffield Three (3DL) and Nuffield Four (4DM) tractor models, including Universal variants, produced from the mid-1950s into the 1960s. These robust agricultural machines, developed by the British Motor Corporation (BMC), were known for their reliable performance and sturdy construction, playing a significant role in British farming. The Nuffield Three typically features a 3-cylinder BMC 3.4T diesel engine producing approximately 35-40 HP, while the Nuffield Four is equipped with a 4-cylinder BMC 4.0 diesel engine delivering around 45-55 HP. Both models utilize manual transmissions with various gear configurations and often offered power take-off options. This comprehensive manual is designed to assist owners, mechanics, and restoration specialists in maintaining and repairing their Nuffield tractors. It provides detailed coverage of all major systems, including engine mechanical and electrical components, fuel and emission control systems, clutch, transmission, driveshaft, axles, suspension, steering, and brakes. The manual also includes extensive information on bodywork, interior components, and electrical systems, along with general information, preventive maintenance schedules, troubleshooting guides, and step-by-step repair procedures. With detailed illustrations, diagrams, wiring schematics, and technical specifications, this resource is an indispensable tool for ensuring the operational efficiency and longevity of these classic agricultural vehicles.