Theis increasing the number of 8×8 Heavy Expanded Mobility Tactical Trucks ( ) it is ordering from , adding $321 million to a contract awarded in early February 2008. The contract modification is funding a total production lot of 1,745 A4 heavy s. Following that award, by October 2008 launched a three-year contract for the procurement of over 6,000 FHTM vehicles worth over $1.2 billion. HEMTT entered service in 1985. Currently the product-improved HEMTT A2s is in production, with A4 upgrades taking effect in July this year. The most recent improvements to the HEMTT A2 are a fully air conditioned cab and cab structural changes that makes installation of add-on-armor in the field quicker and easier. HEMTT is providing the baseline for the ‘Family of Heavy Tactical Vehicles’ (FHTV). With payload capacity of 13-ton and off-road capabilities, HEMTT makes the backbone of the ’s logistics fleet.
HEMTT A4 is powered by a 500-HP Caterpillar C-15 engine. This engine provides 55hp more than the original engine used in the HEMTT. The engine is coupled with an Allison 4500 SP/5-speed automatic transmission, rated for 600hp. This powertrain offers a 1750-lb. torque, gross input, and handles more power and torque for the engine upgrade without changing gear ratios. Survivability and self-protection features are introduced with the standard version. The vehicle is provided with basic armor protection including an Integrated under cab protection, making part of the A-kit, and attachments for add-on B-kit armor, complying with the Army’s Long Term Armor Strategy. The vehicle is also fitted with an integrated mounting for a protected gunner position (GPK) and machine-gun mount on the cab roof. HEMTT A4 will be produced in several models, including the M997A4 cargo, the M-978A4 fuel servicing (tanker), the M1120A4 load handling system variant, M-982 A4 and M-983 A4 tractors, and M-984 A4 recovery truck fitted with cranes and winches.