The Medium Tactical Vehicle Replacement (MTVR) range of vehicles is a family of tactical off-road trucks especially designed by the Oshkosh Corporation to meet the requirements of the United States Marine Corps. From 2000 onwards, MTVR trucks gradually replaced vehicles of the M809 5-ton, 6x6 Truck Series and the M939 5-ton, 6x6 Truck Series then in service with the USMC. Up till today, some 11,500 MTVR trucks have been manufactured, the bulk of these vehicles are serving with the USMC and US Navy. Among the many variants described in this publication are, for example, the MK23 Cargo Truck, MK27 Extended Bed (XL), MK29 Dump Truck, MK31 Tractor and the MK36 Wrecker. Also described are the various add-on armour phases such as the Armor Protection Kit (APK) and the MTVR Armor System (MAS).