In April 1941, with World War in Europe on the horizon once more, the U.S. government entered into a contract with the Studebaker automobile company to begin producing 2.5-ton class military trucks out of its factory in South Bend, Indiana. The three major 2.5-ton American truck producers of World War 2 -General Motors, Internatonal Harvester Company and Studebaker - made about 900,000 trucks in all with GM and IHC providing their product to the U.S. Army, Navy and Marine Corps and Studebaker manufacturing 197,678 trucks for Lend-Lease - these primarily ending up with the Red Army of the Soviet Union. The plan, then proposed by President Roosevelt, was to "lend" or "lease" such military goods to any country whose security was vital to the defense of the United States. The Studebaker US6 saw manufacture from 1941 to 1945.
The original 2.5-ton truck came about through a U.S. military requirement for a cargo hauler produced in large numbers to supply the logistical need of fighting men in combat theaters all over the globe. All of the 2.5-ton trucks produced in America had some interchangeable parts which eased overall production and further helped with repairs abroad. The requirement for moving men, weapons and cargo by traditional means was so great that, in 1942, the Studebaker design was copied and built in Soviet factories to help shore up demand.
When completed, state-side Studebaker trucks were moved by rail to the West Coast to be loaded onto transport ships destined for the warm-weather ports of Iran. 2,803 ships were required to cross the treacherous seas from America when carrying Lend-Lease equipment and supplies. Once unloaded, the trucks were then driven along land routes into Soviet territory. The trucks travelled hundreds of miles over mountain passes and into valleys while crossing deserts before reaching the Soviet Union. The main overland routes to supply aid to Russia from Iranian ports was known as the "Persian Corridor".
The standard haul version of the US6 was the 6x4 tractor form for use with semi-trailers. The trucks were eventually produced in a short (148-in) and long (162-in) wheelbase and in 6x4 and 6x6 wheeled configurations. Since the 6x4 version was intended for on-road use only, its weight classification was 5-ton whereas the 6x6 version was rated using the traditional off-road system of 2.5-tons. The engine of choice became a Hercules 6-cylinder inline, gasoline-fueled engine that produced 94 horsepower at 2400rpm coupled to a five-speed transmission with a two speed transfer case. The truck measured a length of over 21 feet (6.5 meters) with a width just over 7 feet (2.3 meters) and a height of 9 feet (2.8 meters). Most of the trucks had a standard operating crew of two - a driver and an assistant driver. The "shop van" repair variant had an expanded crew of four to operate the hoist and fix flat tires as well as accomplish some types of engine repairs. The truck weighed 10,450lbs (4,850kg) though many were overloaded under the stresses of war and could weigh as much as 16,100lbs (7300kg).
The vehicles could reach top road speeds of 45 miles per hour (70kmh) in the base 6x4 wheel configuration and range was out to 240 miles with the single 40-U.S. gallon capacity fuel tank. The US6 line eventually numbered some thirteen types and arrived in 6x4/6x6-wheeled forms, with short or long wheelbases and with or without a winch system. The most common of the line became the no-frills standard cargo truck version.
Most of the Studebaker trucks were built with a closed hardtop cab based on the civilian Studebaker M-series cab design - as the harsh weather in the Soviet Union essentially required it. The US6 and the GMC CCKW series trucks shared a similar external appearance to one another though closer examination revealed the fuel tank in the US6 set to the driver's side while the CCKW fit this along the passenger side. The US6 cab also featured "swing-out" forward windscreens with roof-mounted windshield wipers. Studebaker continued to employ the small, triangular "venting" window at each cabin door in addition to the typical roll-down window sections. A vacuum-boosted brake system differed from that as found with other manufacturers as well.
The Russian Army particularly enjoyed their Studebaker stocks as they found that the Hercules engine could run on just about any type of gasoline at hand. Standard gross weight limits were regularly exceeded out of sheer necessity and Soviet personnel grew so fond of the American product that they referred to them simply as "Studers". Eventually, various improvised configurations (never envisioned by its American designers) were implemented. The side rails and flat bed were removed and these replaced with a steel pipe framework featuring variable-elevation and traversal using a hand-cranked system. Welded on top of this folding frame were 15-foot steel rails to hold fourteen or more M-13 "Katyusha" high-explosive battlefield rockets. The M-13 rocket was 5 feet, 11 inches long and 5.2 inches in diameter weighing some 93 lbs each. This variant of the US6 was the first mobile rocket projector used by the Soviet Army. The Germans, falling under the lethal reach of such a weapon, nicknamed these rocket launchers as "Stalin's Organ" for their distinctive howling sound when firing. Battlefield rockets, while only accurate to a certain degree, proved a tremendous area-saturation weapon and psychological tool for the Soviets during World War 2.
The US6 was used in many roles across the Red Army - from troop and munitions carriers to artillery mover and battlefield support weapon. In July of 1943, the Soviet Army planned a major offensive against the Germans at Kursk. Soviet General Zhukov became aware of the German battle plan months in advance and knew that the enemy fielded 912,000 men, 2,928 tanks, 10,000 artillery pieces and 2,100 aircraft for the attack. Zhukov then had enough time to amass a much superior force numbering 1,910,000 men, 5,100 tanks, 25,000 artillery pieces, 3,000-plus. The major problem for Zhukov in the upcoming operation would be supply lines as tanks and support vehicles moved ahead across the battlefield. Additionally, there would be difficulty in quickly moving infantry and field guns to advantageous positions along a changing front. The answer to Zhukov's problems were thousands of "Studer" trucks to resupply the vehicles, move artillery and crews, and haul infantry. After the decisive Soviet victory, it became clearly obvious that the role of the US6, as a reliable heavy-duty battlefield truck, played a critical role for the advancing Soviet forces. In appreciation, Soviet leader Joseph Stalin himself sent Studebaker an official letter of gratitude from the Russian people.
With the war in Europe over in May of 1945, production of Studebaker US6 6x4 and 6x6 model trucks was ended in July. Several war time personalities would end up agreeing on the value of the 2.5-ton truck as the one important logistical innovation that really won World War 2 for the Allies - more than any other single "weapon" of the conflict.