The M53 and M55 were a pair of self-propelled guns developed concurrently shortly after World War II that featured identical chassis and turrets, differing only with regards to armament. Design consisted of a chassis that was taken from the M47 tanks but which was inverted, thereby leaving the powerplant a the front of the vehicle. This left no space for the driver which necessitated an unconventional arrangement of having the driver placed inside the turret on a special forward-facing seat that did not move when the turret changed direction. The turret was fully enclosed but had two large hatches in the rear that could be opened to provide a platform for the gun crew. Armament consisted of a 155-mm gun for the M53 or an 8-inch M47 howitzer for the M55, both of them using the same M86 mount, and providing powered traverse and elevation. However, storage capacity was weak, as the M55 could only carry ten rounds inside the turret. Defensive armament consisted of a .50-in Browning machine gun but there was no NBC protection for either vehicle, nor were they amphibious or air transportable. All US Army M53s were coverted into M55s just a few years after their introduction although the USMC retained theirs, and they went on to serve in the Vietnam War before being replaced in the 1960s by the M107 and M110. Export customers included Belgium, Germany, Turkey, Spain, and Taiwan.

The initial requirement for a new 155-mm gun motor carriage was established in 1946 with the initial prototype T97 delivered in April 1952. The prototype of the 8-inch version was known as the T108 and delivered just a few months later, in July. They entered service that same same as the M53 and M55. Incremental improvements were given throughout their service life but no additional variants were produced.