This workshop service manual covers the Allis-Chalmers D-15, a versatile utility tractor produced primarily from 1959 to 1964. Designed for general farm work, cultivating, and powering implements, the D-15 was known for its adaptability and robust features, including a standard 540 RPM Power Take-Off (PTO) and a capable hydraulic system. It offered both gasoline and diesel engine options, typically featuring a 4-cylinder overhead valve engine with approximately 34 PTO horsepower for gasoline and 30 PTO horsepower for diesel variants. The D-15 competed with major manufacturers of its era and remains a valued machine for its utility and engineering. This comprehensive manual provides detailed repair and service information essential for maintaining the Allis-Chalmers D-15. It covers all major systems, including the engine, fuel, cooling, ignition, electrical, transmission, hydraulics, steering, braking, axles, chassis, and body. Within its extensive pages, you will find step-by-step instructions for maintenance, troubleshooting, component overhaul, and adjustments, along with critical specifications and tolerances. This resource is designed to assist owners, mechanics, and technicians in effectively servicing and repairing the D-15, ensuring its continued reliable operation.