These are highly detailed Specification Booklets with most of them comprised of 32 pages. They all show cross-section drawings of components and illustrations of related assemblies such as track roller frames, main-frames, power train components, and engines.  There is abundant data susch as horsepower, speed, dimensions, capacities, weights, and etc.  These are a must have for the collector of Tracktype Tractors memorabilia.  The D6 Engine crosssection is representative of the amount of details for all of the models.  There are 3 booklets for the D6, 2 for the D7, 4 for the D8, and 2 for the D9.