appearance. No new A3 standard-transmission vehicles were produced, all vehicles being upgraded from previous configurations during the rebuild process. The exception is some M109A3 shop vans. A small number of M109A3s were upgraded to A4 specifications using the M35A3 upgrade parts and procedures. As-built original Pre A2s are gasoline-powered, A1s use the LDS 427-2 multifuel engine, A2s use the LD/LDT 465-1c multifuel engine, and A3s use the Caterpillar diesel. It is common, however, to find rebuilds of former gas-powered REO and Studebaker models having A1 and A2 multifuel configurations. The original contract for the M35 - Service Life Extension Program was competitive. The last two companies to send vehicles to Aberdeen Proving Ground were AM General, South Bend, IN and Cummins Military Systems, Augusta, GA (AMG was awarded third quarter of 1993). Brakes Brake system is air-assisted-hydraulic six-wheel drum brakes with a driveline parking brake, although gladhands exist on the rear of the vehicle for connection to trailers with full air service and emergency brakes. Braking performance of the truck is similar to other power drum brake vehicles of this size. Each drum was designed with maximum efficiency in mind, and individual drums can dissipate up to of braking heat. Due to this brake system and GVWR under , the M35 can be driven without a commercial driver's license in most states. Electrical The electrical system is 24 volt, using two 12 volt 6TL-series military grade batteries run in series. Operational history The M35 family was introduced in 1950 to replace the GMC CCKW and M135 family cargo trucks that constituted the backbone of U.S. military transport since their introduction in World War II. The M35 would not completely replace the M135 family until the middle of the 1960s. However, the M35 would quickly become the dominant truck in its class in the U.S. military, serving with all the services in various capacities. For a short period the M35 was called "The Eager Beaver" by the U.S. Army due to its fording ability. But the name was never popular and forgotten in a few years. The M35 series was to be replaced by the Light Medium Tactical Vehicle. However, many United States National Guard and Reserve units continued to use them as the new family of vehicles was phased in. The M35 series was used by the United States in Iraq during Operation Iraqi Freedom. M35 series vehicles were known