This manual covers the Allison MT(B)600 Series automatic transmissions, designed for a variety of heavy-duty applications including buses, commercial trucks, and specialty vehicles. These transmissions are known for their robust engineering and reliability, often paired with heavy-duty diesel engines. The MT(B)600 Series typically features five or six forward gears plus reverse, incorporating a torque converter and often integrating with an Electronic Control Module (ECM) for optimized performance. While specific dimensions and weights vary by application, the core design emphasizes durability and efficiency for demanding operational environments. The purpose of this factory service repair manual is to provide comprehensive guidance for the maintenance, diagnosis, and repair of the Allison MT(B)600 Series transmissions. It details essential procedures, including fluid service intervals, oil capacity, and recommended fluid types, all of which are critical for ensuring longevity and optimal performance. The manual also covers diagnostic codes, component testing, and disassembly/assembly procedures, making it an indispensable resource for owners, technicians, and mechanics. This English-language manual is designed to facilitate accurate upkeep and effective troubleshooting, ensuring the continued operational integrity of these transmissions across all covered years.