Caterpillar D6 seriesThe early Caterpillar D6 tractors – long-term survivorsContrafed PUblishingMay 3, 2016September 25, 2021 by Contrafed PUblishingMay 3, 2016September 25, 2021 For over 80 years, the Caterpillar D6 has been the backbone of the medium size Cat track type tractor range. Here is an overview of...