Wow looks like we were both right, part International and part chevrolet trucks.
Tow Mater or just Mater (Tow is his first name and Mater is his last name) Type of Vehicle: An Old North American Tow Truck or a 1951 International Harvester L-170 "boom" truck with elements of a mid-1957 Chevrolet 3800. One-Ton Wrecker Tow Truck.