The K-31 Truck was used as the Power Truck for the SCR-270 radar. It was also used to house several (radio) equipments of the Signal Corps and Army Air Force.
US Army Photo: right side without window (other than the K-30 truck
Second version (B) on Autocar, truck 5-6 ton, 4x4, COE, VAN, U8144 with somewhat different York Hoover van body:
TM-11 1510 is prove that the K-31 truck was indeed the Power Truck of the SCR-270 and the K-30 truck the Operating Truck though the both are sometimes confused.