to replace both the M47 and the M59, as well as the M135-based M215. Also under the M45 chassis was the signal corps V-17 pole derrick, and the V-18 auger truck, later replaced by the M35 upgrade below. The M756 was a specialized pipeline repair vehicle, the M763 was designed for telephone line repair, and the M764 was a specialized earth-boring and pole-setting variant. Gun trucks The versatility of the pattern was perhaps shown best in its usage as an armored "gun truck" for patrol duties and convoy escort. The simplest examples were produced by simply placing an existing light gun mount directly onto the cargo bed of the truck, and securing it in place. No armouring or special support equipment was installed. One such conversion was performed in Congo-Leopoldville in 1965, using an Oerlikon GAI 20 mm anti-aircraft gun. Another conversion in the Congo entailed mounting pods with 2.75" aircraft rockets on a pedestal on the cargo bed, but this proved unsuccessful. The first more sophisticated conversions of the pattern were performed by the U.S. military in Vietnam. U.S. Army Artillery Battalions (Automatic Weapons, Self-Propelled) were often assigned Artillery Batteries (.50-caliber), units equipped with M35 trucks and M55 Quadmount systems mounting four M2 Browning machine guns. Units were also authorized a single M60 machine gun and M79 grenade launcher. While the M35 was designed to act as the prime mover for the M55 Quadmount system, which included a towed trailer, the M45 mount was often removed or the wheels removed from the trailer, and the system mounted on the bed of the truck. The M55 system was also mounted on the M54 truck. More simplified armoring projects were conducted as well, adding armored walls of various thicknesses to standard cargo variants. A smaller bed-mounted multi-angle "box" was also tried. U.S. Army gun trucks used a wide variety of weapons including the M2 Browning machine gun, M60 machine gun, and even the M134 Minigun. At the end of the Vietnam War most of these vehicles were returned to their standard configuration, except for a single original example shipped to the U.S. Army Transportation Museum at Fort Eustis, Virginia in 1971. Numerous Vietnam veterans have expended countless hours to build full size replicas of their original Gun Trucks, using M35, M54, and even Army Dump Trucks as platforms, much the same as these veterans did in Vietnam. A functional display replica