M1064 mortar carrier

The M1064 mortar carrier is a tracked, self-propelled artillery vehicle, consisting of the M120 mortar mounted on a M113 chassis.

The design consists of the M298 Cannon, M191 Bipod, M9 Baseplate, and the Carrier Adaption Kit. With the use of an auxiliary M9 Baseplate and extension feet for the M191 Bipod, the M121 can be dismounted from the vehicle and emplaced for ground-mounted operation.

Source
This article incorporates work from http://www.army.mil/factfiles/equipment/indirect/m120.html, which is in the public domain as it is a work of the United States Military.