The Medium Tactical Vehicle Replacement (MTVR) is a series of vehicles used by the U.S. Marines. The first MTVRs were delivered in late 1999. The MTVR is the equivalent of the U.S. Army’s Family of Medium Tactical Vehicles (FMTV); the Marines do not use the FMTV (with the exception of the FMTV-based HIMARS) and the Army does not use the MTVR. There were originally four, later seven, MTVR variants, then nine (plus a sub-variant) as deliveries and development continued. A dedicated trailer and prototype/developmental MTVRs have also been produced. The MTVR was designed and is manufactured by Oshkosh Defense. Development and production history The MTVR has its design origins in two U.S. military programs, the 5 ton Tactical Truck Replacement (5TTR) for the U.S. Army, and the Medium Tactical Vehicle Replacement (MTVR) for the U.S. Marines. The aim of these programs was to upgrade and extend the service life of around 3,400 U.S. Army M939 series 5 ton trucks, and 8,100 U.S. Marines M809 and M939 series 5 ton trucks. Prototype and development contracts for both programs were awarded in 1996. The 5TTR program was subsequently halted, and the MTVR program evolved from an upgrade to a new-build requirement. Oshkosh was awarded a multi-year MTVR production contract in February 1999. The first vehicles were scheduled for delivery by the end of 1999, and deliveries under the initial contract concluded during August 2005. The award initially allowed for up to 8,168 MTVRs (including options for 2,502) in four variants (MK23, MK25, MK27, MK28) to be ordered over five program years; 6,931 MTVRs were delivered, 6,393 to the Marines and 538 to the Navy (Seabees). The first MTVRs were fielded in July 2001. Three additional variants followed, the MK29, MK30 and MK36. Under a separate contract, Oshkosh commenced production in July 2004 of a further MTVR variant, the MK37. Based on the MK27 and fitted with a rear-mounted Hiab materials handling crane rated at 10,000 lb at 10.5 ft maximum reach, the MK37 is a resupply vehicle for the U.S. Marines HIgh Mobility Artillery Rocket System (HIMARS). The companion trailer is designated MK38. Oshkosh was awarded a second MTVR multi-year contract (FY05-FY10) in July 2004. This award initially covered only potential Foreign Military Sales (FMS), plus the continuing requirements of the U.S. Navy. Ultimately the U.S. Navy and Marines combined received >2,000 vehicles under this contract. In 2005, the MK31 Medium Equipment