This manual contains maintenance information for the 5 ton M939 US Military Trucks. This is volume 1 of 4 in the Direct / General Support Manual Series. M939 series trucks are a 5 ton heavy duty 6x6 truck. Cargo versions were designed to transport 10, 000 pounds of cargo in all terrain and all weather conditions. Originally designed in the 1970's to replace the M39 and M809 series of vehicles. 44, 590 units were produced. This manual is printed to help private owners in the maintenance of their vehicles.