As the 2008 production year dawned, Navistar International (known in the world market as a builder of heavy-duty trucks) thought it needed another way to introduce its new line of Class 8 tractor trucks-the Lonestar-to the public. This big truck is powered by a Cummins ISX twin-turbo diesel engine, which is one impressive motor in both size and performance. But of more particular interest is the Lonestar's exterior styling-it's a pure throwback to truck designs of bygone eras, most notably the '39 International D-series. As Navistar refers to it: "Advanced Classic" innovation and technology.

Shaking up the tractor truck market is one thing, but having the right promotional tool is necessary, too. That's why International also decided to retrofit one of Navistar's 7-liter MaxxForce 7 twin-turbo diesels into a vintage '39 International truck. Possibly the largest engine many have ever seen stuffed between the framerails of a 1/2-ton pickup, this was one enormous undertaking, which is why American Speed Company in Plymouth, Michigan, got the call to build it.

American Speed, headed Mark Trostle, was already busy in production of its Speed33 steel convertibles, but took the International project on with its usual expertise. What they soon found out is it's one thing to say, "Use this motor and build this truck," and quite another to engineer everything so it'll work correctly together, but that's what they do so well. The first order of business was to locate a reasonable starting point, which came to light when an International dealer in Ohio was located with the right truck: a solid, '39 International D-series pickup.

Once back at its shop, American Speed did some analysis to figure out how they were going to shoehorn the big engine and Allison transmission (with a combined weight of 1,500 pounds) into the framerails without affecting the truck's vintage look. As it turned out, the team decided to shorten the original 'rails by 5 inches to make things line up correctly. They boxed the 'rails while they were at it, and created new crossmembers for the motor and trans. Since there wouldn't be room for the Universal aluminum radiator to be mounted in its conventional spot, American Speed chose to move the radiator to the truck bed and run its water lines through the framerails.

The rearend is a 9-inch Ford Tru-Trac posi unit (3.50:1) that works with a set of Air Ride Technologies 'bags. Up front, independent A-arms and spindles from R&C Motorsports and Steer Clear steering components from Wizard were employed along with another pair of Air Ride 'bags.