The M39 Armoured Utility Vehicle was a prime mover and reconnaissance vehicle based on the chassis of the M18 76mm Gun Motor Carriage (Hellcat). The M18 with its powerful engine, torsion bar suspension and comparatively light weight, was the fastest armoured vehicle to see service with the US Army during the Second World War. By the summer of 1944 it was clear that the M18 would soon be superseded by the M36 90mm Gun Motor Carriage, and production of the gun armed M18 ended in October 1944.
Although the M18 was no longer to be produced as a tank destroyer, its high speed and low profile meant that the basic chassis was too good to waste. In June 1944 it was decided to develop a prime mover and reconnaissance vehicle that would use the chassis, engine and suspension of the M18, but with the turret removed. The new vehicle was given the designation T41 Armoured Utility Vehicle, and was ordered into production.
Two test vehicles were produced by modifying existing M18s. They had their turrets removed and the internal layout altered. The superstructure was extended slightly upwards. In the new format the T41 needed a crew of two and could carry seven passengers. It could carry one anti-aircraft machine gun on a mount at the front of the new fighting compartment. The standard M39 had an open topped fighting compartment, although some armoured covers were produced
Production began in October 1944 when the first ten were completed. Another sixty were built in November and production then picked up speed, with 163 in December and 180 in January 1945. A total of 640 had been built when production ended in March 1945. The T41 was standardized as the M39 Armoured Utility Vehicle early in 1945.
The M39 was used as the prime mover for the 3in M6 towed anti-tank gun. In this configuration the vehicle could carry 42 rounds of 3in shells.
It was also used as a reconnaissance vehicle or a troop carrier. The reconnaissance vehicles and troop carriers were designated the T41 E1. They suffered from thin armour and a lack of overhead protection which meant that their crews were vulnerable to even small arms fire.
The M39 remained in use with the US Army until the end of the Korean War. In Korea they were used as cargo carriers and personnel carriers, and played an often vital part in the defensive battles of the later stages of the war, allowing reinforcements to reach the frontline or troops to be evacuated from vulnerable outposts. By this point the M75 armoured infantry vehicle had entered service, and the extra protection it provided was greatly valued.
The M39 was the basis of three further modifications - the M44 Armoured Personnel Carrier, the T17 Command Post Vehicle and the T65 Flame Tank.