Which engine, cited for its durability in heavy-duty applications, began production around 1984?

Cummins B-Series diesel inline-six.

In the context of modern, long-lived engine architecture that demonstrates endurance through iterative improvement, the Cummins B-Series diesel inline-six is frequently highlighted, especially for heavy-duty sectors. This engine platform commenced production around the year 1984 and has gained renown for extreme robustness, with individual units reportedly surpassing a million miles in service. While Clessie Cummins' earlier work included restoring the 1919 6hp Hvid oil engine, the B-Series represents a continuing, successful engine blueprint still powering contemporary commercial vehicles like Dodge Ram trucks.