Instructions
Learn the history of the company. Knowing something of the background helps collectors identify products. For instance, although many people know Tonka dump trucks, the company created only a crane and steam shovel during the first two years of production, and the Winnebago wasn't introduced until 1973.
Look for the official Tonka decal on the side of the truck. It displays some variation on the basic company information: Tonka Toys, Mound Metalcraft, Mound, Minn.
Find "TONKA" embossed into the metal. Many of the trucks are stamped on the tires, the grille and the tailgate.
Check sources for the little details that will authenticate the toy. For example, the hubcaps on the 1954 to 1957 models contain five round holes while the prior models have no hubcaps.