This manual covers the Case International S, SC, and SO Series Tractors, produced generally from the mid-1940s through the 1950s. These tractors represent a foundational line of utility vehicles from Case IH, known for their reliability and consistent pulling power at lower RPMs. Designed with a focus on operator awareness and machine stability, these models feature a straightforward mechanical design, emphasizing operator comfort, control layout, and essential safety procedures. Their robust construction and simple, effective engineering made them dependable workhorses for agricultural tasks during their production period. This Operator's Manual provides essential guidance for owners and operators of the Case International S, SC, and SO series tractors. It details safe and efficient operation, covering key areas such as engine operation and basic checks, transmission functions including clutch and PTO, hydraulic lift operation, steering system mechanics, and basic electrical system maintenance. The manual also outlines crucial routine procedures like startup and shutdown, daily checks, lubrication schedules, and essential maintenance tasks for filters and fluids. It offers basic troubleshooting advice for common operational issues, focusing on operator-level maintenance rather than in-depth mechanical repair.