I photographed this Clark Airport Tug (possibly a CT-40 model) at the Museum of Mountain Flying in Missoula, Mont. The one in Rexburg seems to be a slight variation of the same tractor.
This is a modern development from the Clarktor Tractors used during WWII
Clark CT30 Airport Tug
Missoula, Mont. 2021
Missoula, Mont. 2022
Clark Airport Tug (assumed)
This appears to be a slight variation of the Clark tarctor in Missoula (above).