Caterpillar Tractor Co. identifies the truck engine market as a dynamic, demanding opportunity for creative utilization of corporate technical, manufacturing, and marketing resources. With the objective of more completely serving the needs of this industry during the balance of the decade, a new family of heavy-duty truck engines is being developed to cover the range of 270-750 hp. Design parameters were formulated to a large extent from a corporate perception of what is possible and practical in the development of diesel engines, from marketing projections of horsepower and operational expectation trends, and from discussions with truck manufacturers for their perception of future requirements. Program objectives were established to assure meeting those requirements. The installation of the 3406 engines, which are in limited production, is shown in various truck models.