This workshop manual provides comprehensive coverage for International Harvester Engines, specifically detailing service and repair procedures for models 155, 246, 179, 268, 206, 310, 358, DT 239, 358, and 402. It also extends to tractor units 2400 and 2500, along with engine models 454, 474, 475, 574, and 674. This manual is designed to be an essential resource for maintaining the operational integrity and longevity of these robust International Harvester powerplants and associated equipment. The purpose of this manual is to equip owners, mechanics, and technicians with the detailed knowledge required for effective maintenance and repair. It encompasses a wide range of critical information, including step-by-step service procedures, diagnostic troubleshooting guides, essential technical specifications, and vital safety guidelines. By adhering to the instructions and specifications outlined within, users can ensure that their International Harvester engines and tractor units perform optimally and reliably.