The Nuffield Universal Three (3) tractor, model series code 3DL, represents a robust and reliable general-purpose farm tractor produced in England from the early to mid-1960s, typically between 1962 and 1968. As a product of Leyland Motors, later part of British Motor Holdings and British Leyland, it embodies a heritage of solid engineering. This agricultural machine, powered by a 3-cylinder BMC diesel engine, offered approximately 40-45 PTO horsepower, making it suitable for a wide range of farm tasks. Its design prioritized functionality and durability, positioning it as a dependable workhorse against competitors like Massey Ferguson and Fordson. This factory service repair manual provides comprehensive, in-depth information for the Nuffield Universal Three (3) tractor. It covers essential maintenance procedures, including routine servicing, lubrication, and fluid checks, as well as detailed troubleshooting guides to diagnose and resolve common issues. The manual delves into the overhaul and repair of all major systems, such as the engine, fuel, cooling, lubrication, transmission, and hydraulic systems. Additionally, it includes guidance on electrical components, steering, braking, axles, and chassis. This resource is designed to assist owners, mechanics, and technicians in maintaining the optimal performance and longevity of their Nuffield tractor.