Caterpillar D7C/D7D Crawler Tractor
The Caterpillar D7C crawler tractor was first produced in 1955, replacing the D7B model. In many areas, it was popularly known by its serial number prefix: 17A.
With serial number 17A0409, a new feature, the hydraulic tracks adjuster, was introduced. In 1959, with serial number 17A11981, a turbocharger became standard equipment and the model designation changed to D7D (also know as the Turbo 17A).
Based on data from the sales database of Ritchie Bros. Auctioneers, it is estimated that more than 19,000 Caterpillar tractors with the 17A serial number prefix were produced.
Production of the D7D ended in 1961, it was replaced by the Caterpillar D7E.