While the 2 1/2-ton chassis has been used a platform for a variety of interesting trucks, most are relatively mundane service vehicles. Even when equipped with a ring mount and 50-caliber machine gun, the “deuce and a half” is hardly threatening. That is not the case with this version, however. Armed with a one-ton, 19-foot long Lacrosse missile, capable of carrying a nuclear warhead, the M398 could have dominated the battlefield.
The guided missile normally carried a single, 540-pound, shaped-charged warhead, although it could carry high explosive conventional, chemical as well as atomic warheads.
The operational vehicle issued was the M398 Guided Missile Launcher Truck, Helical Railed. The truck was based on the M45 154-inch wheelbase, gasoline-powered chassis with dual 9.00-20 rear wheels. The M398 vehicle became the operational mount for the Lacrosse Type I Guided Missile in 1958. With the launcher in the transport position, the M398 was 21' 11" long overall, 7' 10" wide and 9' 8" tall. The helical rail of the M398 launcher gave a 500-degree per second roll to the missile for improved accuracy.
Although issued to troops, these trucks were never used in a combat situation.