This manual pertains to the Allison 4000 RDS transmission, a robust component designed for demanding applications. Featuring 4th Generation Controls, this transmission offers advanced operational capabilities, with options for power take-off (PTO) and an output retarder to enhance versatility and performance. The engineering behind the Allison 4000 RDS prioritizes reliability and efficiency, making it a trusted choice for various commercial and industrial uses. This comprehensive Factory Service Manual in English provides detailed guidance for the maintenance and repair of the Allison 4000 RDS transmission. It covers essential areas including general information, preventive maintenance, general overhaul procedures, transmission disassembly, module rebuild, assembly, and wear limits and spring data. The manual is equipped with numerous line drawings, cross-sectional views, exploded views, and a hydraulic schematic to aid understanding, empowering owners and technicians to perform accurate diagnostics and repairs, ultimately saving expenses through enabling DIY repairs.