Type classified in March 1963 as a mobile command post, the M577 has also been utilized as a mobile field aid station, artillery fire direction center, and communications vehicle. Essentially a vertically expanded M113 armored personnel carrier, the interior of the M577 has been reconfigured to accommodate additional communications equipment, map and tactical information boards, field desks or artillery plotting tables, and additional crewmembers. Each 577 is equipped with an externally mounted electric generator capable of powering the additional equipment to reduce loading on the vehicle's inherit electrical system. In addition, each M577 is equipped with an integral expandable shelter which can be deployed when the vehicle is stationary. In a tactical situation, multiple M577 shelters can be linked together to create an enclosed working space. Like the M113, the M577 is amphibious, and is equipped with a diagram for load equalization, necessary to counteract the M577s high center of gravity. The M577 is equipped with a standard M113 driver's hatch and a single vehicle commander's hatch centered in the roof of the vehicle. The commander's position is equipped with a pintle machine gun mount which may accommodate either an M2 HB caliber .50 machine gun, an M60 7.62mm machine gun, or a Mk19 40mm grenade launcher. The vehicle is equipped with an engine driven Nuclear, Biological, Chemical, filtration system which supplies the crew with purified air via a protective mask hose coupling, but does not over pressurize the crew compartment. Since it's introduction, over 4,000 M577, M577A1, and M577A2 command vehicles have been produced for the United States Army.
The M577 is very similar to the M113 in appearance. The driver is situated in the left front corner of the vehicle, while the powerpack is located in the right front corner. The M577 retains the M113's torsion bar suspension, utilizing five pairs of evenly spaced aluminum alloy cast road wheels with the drive sprocket in front, the idler wheel to the rear, and no track support return rollers. The track is a steel single pin variety with each track block riding on a replaceable rubber pad. As with the M113, the M577 is fully amphibious, and is equipped with a driver deployable trim vane mounted on the front slope of the hull. The M577 is propelled through the water and maneuvered by track manipulation.