SPG on the M5A1 chassis designed for jungle warfare. The vehicle featured a 105 mm light howitzer mounted in an open-topped cabin. Development started in November 1943. In August 1944, two prototypes underwent trials on the Aberdeen Proving Ground. On June 21, 1945, the project was discontinued due to the lack of interest in vehicles of this type.
Characteristics are specified for vehicles with crews trained to 100%.