In the heavy-truck industry, the loyalty to a particular brand of engine is every bit as strong as - if not more than - one's affection for the chassis in which it's placed, a customer buys a vehicle from one manufacturer and then specifies an engine from another.

The heavy-truck business has gone in the other direction of less vertically integrated, with chassis vendors bringing engine development in-house. This could leave enginedrivetrain manufacturers such as Cummins and Caterpillar out in the cold. Cummins in particular is said to be in potential trouble, as it doesn't have its own line of off-highway equipment like Caterpillar.