It has a 203.2 mm (eight-inch) howitzer which can traverse 30° left or right, carrying 10 rounds of ammunition when fully combat loaded.

The gun has a maximum range of 10.51 miles (16.92 kilometers) with a rate of fire of one round every two minutes.

The crew consists of six - a driver, commander, gunner, and three loaders.

[1] The M55 is lightly armored, 25 mm maximum, but sufficient to protect the crew from indirect artillery hits and small arms fire.

The engine is mounted in the front and is driven through a front-drive sprocket capable of a top speed of 30 mph (50 km/h).