V12 John Deere 8960 Built to Break Rules

The Wild Story of the V12-Powered 8960 That Shook the Corn Off Iowa

Some machines are built. Others are forged—in backwoods shops, under calloused hands, with zero regard for warranty, EPA compliance, or common sense. This is the story of the latter.

In the summer of 1990, a brand-new John Deere 8960 rolled off the Waterloo line with factory-fresh paint and corporate-approved horsepower. Sixty days later, it would leave a different kind of shop entirely—with 625 horses under the hood, twin stacks that let the V12 engine breathe, and nearly 50,000 pounds of raw, re-engineered fury.

No, this isn’t a tall tale from some tractor-pulling Facebook group. This was real. It happened. And the madman behind it allb was a brilliant gentleman by the name ofvBill Dietrich.

For those unfamiliar, the John Deere 8960 was the top-dog four-wheel-drive tractor in Deere’s lineup in 1990. It came from the factory with a Cummins N14, an 855 cubic inch inline-six cranking out a respectable 375 horsepower. It was a behemoth of a tractor at the time, meant for the heaviest fieldwork in the Midwest—pulling big implements and plowing through soil like a hot knife through butter.

But in the hands of the right (or wrong, depending on how you view mechanical stability) person, it became something entirely different.

The victim—I mean, platform—was picked up brand new in June 1990, straight from the Waterloo plant. Instead of heading to a field, it was trailered straight into the shop at DMI, where Bill Dietrich had plans. Big, V12 plans.

If you’ve spent time around agricultural equipment, especially tillage gear, you’ve probably heard of DMI—Dietrich Manufacturing Inc.. Founded by Bill Dietrich, DMI was known for pushing the boundaries of ag innovation. They weren’t afraid to challenge convention or crack a few frames in pursuit of more efficient, aggressive tillage systems.

This V12-swapped 8960 was never part of a product line. It was personal. It was Bill, unfiltered. And it remains one of the most iconic—and least replicated—builds in large tractor history.

The Beast Under the Glass

Instead of the stock Cummins inline-six, Bill shoved in a Caterpillar 3412 V-12 diesel. This wasn’t some “drop-in and hope for the best” swap. The 3412 is a 27-liter industrial monster—typically reserved for mining equipment, generators, or anything else that requires turning the Earth off its axis.

To make it fit, the frame had to be stretched 12 inches. The hood was raised 5 inches. An extra 12-inch side panel filled in the length, and a 5-inch filler strip beneath the factory hood section tied it all together. Somehow, Bill made it look like it belonged—like John Deere had secretly experimented with a V12 variant and never told anyone.

The numbers? Stock from Deere: 375 hp and 33,000 pounds. After Bill was done: 625 horsepower and a staggering 49,000-pound curb weight.

Perhaps the best part about this insane build is that it wasn’t just for show- This thing worked. It pulled. It ran. And when it fired up, it sounded like a cargo ship taking off from a cornfield. The DMI team had developed this tractor to travel the country, showcasing the DMI tillage equipment of the time and it did it insanely well as you can imagine.

Everything about it was overkill. Beautiful, impractical, glorious overkill.

In a world that increasingly prioritizes safety warnings, emissions compliance, and factory reliability, there’s something deeply satisfying about a story like this. A man, a shop, a brand-new  tractor—and the desire to give it a soul it was never meant to have.

Bill Dietrich didn’t just re-power a John Deere. He rewrote the rulebook for what “tractor performance” could mean. And in doing so, he built something that still gets whispered about 30 years later in sheds, shops, and diesel forums across the Midwest.

The V12 8960 is more than a machine. It’s proof that sometimes, the wildest ideas are the ones that last the longest.

Because horsepower may fade. Paint may chip. But legends? Legends never die.

Photos by Dustin Korth