M151 MUTT (Military Utility Tactical Truck)
4x4 Multi-Purpose Light Utility Vehicle
The M151 MUTT multi-purpose light vehicle replaced the Korean War-era M38 series Jeeps.
Authored By: Staff Writer | Last Edited:
Prior to the adoption of the ubiquitous HUMVEE multi-purpose 4x4 vehicle, the US military relied on the world renowned "Jeep" emerging from the fighting of World War 2 (1939-1945). The original design came about from the engineers at Bantam to which then the US Army opened prototyping to include both Willys-Overland and Ford Motor Company using the original Bantam work. The Willys MB was accepted for service in 1941 and its history was all but assured. The vehicle then grew into a myriad of battlefield roles and was shipped to far off places in the world through direct export and Lend-Lease. Overall, some 634,000 examples were produced through a combined Willys/Ford effort. While the vehicle certainly played its role well, it was not the final solution in the US military light 4x4 vehicle requirement. When an improved form was sought, Willys-Overland delivered the post-war M38 series, by this time officially trademarking the "Jeep" name. A limited force of these vehicles managed service in the Korean War (1950-1953) though they were largely still outnumbered by World War 2-era variants. The M38 existed through the base M38 and improved M38A1 with production exceeding 160,000 units.
Still searching for a better multirole 4x4 solution, the US Army gave thought to yet another light truck requirement which fell to Ford in 1951. Ford engineers returned with what would become the official successor to the M38 line - marking the end of the World War 2-related Jeeps. The Ford submission was designated in US military nomenclature as the M151 to which the further technical acronym of "Military Utility Tactical Truck" (MUTT) was given. Despite its clear Willys MB/M38 influence, the vehicle proved something of a large departure from the wartime Jeep.
The M151 was specifically classed as a "1/4-ton light tactical truck" and powered by a 71-horsepower Ordnance Continental 4-cylinder, gasoline-fueled engine. This was mated to a 4-speed (1 reverse) transmission system. Dimensions included a length of 133 inches, width of 64 inches and height of 64 inches. The engine was fitted to the front of the vehicle in a conventional automobile arrangement. Body construction utilized a monocoque steel body/frame approach unlike the separate steel tubing / steel frame approach to the Willys series and promoted more internal space, a higher ground clearance and lower center mass. Rounded inlaid headlamps continued the "Jeep" appearance though, the MUTT being a Ford-centric product, the grill was comprised of horizontal slats instead of the trademarked vertical lines of the Willys product. The wheels were set at the extreme corners of the frame. The driver sat at center-left with a passenger at center-right. The forward windscreen, as in earlier Jeeps, could be collapsed over the hood to provide unfettered access for long-barreled weapons such as recoilless rifles or similar. Additional passengers could be transported across bench seating at the rear or they replaced by supplies and equipment.
The MUTT departed from conventional Jeep design in one major way - its use of independent suspension unlike the original's solid axle arrangement. The new system allowed for better cross-country performance and, coupled to the stronger engine - improved performance across the board. However, these changes came at a price - it was later found that M151s were considerably more prone to rollover accidents when taking turns at speed or under heavy mission loads. The primary culprit was found to be the rear wheels which tended to slide under the frame during such actions, leading to rather lethal circumstances that followed. As many drivers were conditioned to the more rigid driving qualities of their Willys MB and M38 models, it made for a more attentive experience when attempting to control the newer M151. It was this rollover issue that prevented the M151's civilian sale - unlike previous Jeep lines.
Original production batch models of M151 MUTTs emerged in 1960, officially replacing the M38A1 line. Ford production was joined by Willys-Overland (now Willys Motors and then becoming Kaiser-Jeep). Interestingly, more production stemmed from the Willys/Kaiser brand label than from Ford who was already busy managing a profitable civilian automobile market.
Aware of the roll over issue centering on the rear wheels, the US Army then looked to rectify the potentially disastrous long-term investment. Additional work led to the refined M151A2 which entered production 1969 with a new, fully-redesigned rear suspension arrangement. While a beneficial solution, it was also deemed prudent to institute a fixed roll bar assembly to further protect M151A2 drivers and passengers.
Altogether, the M151/M151A2 was produced in over 100,000 examples by Willys/Kaiser/Ford. Manufacture spanned from 1959 to 1982.
In practice, the M151 certainly served its calling well. As America had become embroiled in the Vietnam War (1955-1975) - and the MUTT being fully-entrenched in service - M151 trucks were deployed throughout frontline and secondary roles. From this, a plethora of battlefield forms were envisioned including both armed and unarmed variants including ambulances. M151s, despite their inherent deficiencies, performed as admirably in the conflict as their preceding World War 2 counterparts some generations before. Understanding the MUTT's light truck mechanics certainly aided in a driver's control over his rather temperamental vehicle. In the end, the M151 gave a good account of itself, regardless of the ultimate American withdrawal from Southeast Asia in 1975.
Despite its combat theater showing, the M151 still proved no better an answer than the light 4x4 vehicles before it and was officially replaced itself by the all-modern HUMVEE multi-role vehicle by AM General beginning in 1984. As the new design proved dimensionally larger and heavier than the M151, stocks of MUTTs were kept in reserve by the various American service branches for the value they still held. Collections served throughout some of the notable engagements of the 1980s and into the 1990s, usually under special warfare groups and airborne detachments where their mobility, transportability and speed was highly prized. M151s could be hauled by base medium-lift helicopters unlike the HUMVEE systems that replaced them. Many foreign operators of the MUTT still operate their M151s today despite the system's 1960s origination.
The USMC and 82nd Airborne were two notable forces deploying the M151 Fast Attack Vehicle (FAV) mark and these were appropriately armed for the role. For a time, the M151 was a NATO light truck staple while some 100 nations eventually fielded the type in one form or another - a testament to this Cold War-era's sound design, even while attempting to replace a war time hero in the Willys line.