At Deer Park Diesel, we’re no strangers to truck builds—but this 2005 Dodge Ram 2500 5.9L Cummins project has been one of our favorites. When we first got it, the truck didn’t run at all. But we knew it had potential. This build has evolved into the perfect combination of reliable diesel power and street-driven performance.

Starting with the Heart: Upgrading the Cummins Engine

We began by installing a DFC Tow Haul Series 5.9L Cummins long block. We’ve used DFC diesel engines in several builds and can confidently recommend them for both quality and reliability. Their engines come well-packaged, ship efficiently, and deliver consistent performance.

To support the engine, we upgraded the fuel system with an AirDog 2 4G lift pump paired with a Bosch CP3 injection pump. Our target wasn’t insane horsepower—we wanted a hot street truck: quick, responsive, and reliable enough for everyday use.

We installed:
- 30% over injectors from Dynamite Diesel Products
- A 67mm Stealth drop-in turbo from Calibrated Power
- A Steed Speed exhaust manifold
- A Fleece Performance fuel distribution block
- A remote-mount oil catch can
- A fuel filter delete block

First Start, First Impressions

When it fired up for the first time, the truck was exactly what we had envisioned—a street-friendly 500–600 HP diesel build that’s incredibly fun to drive.

Transmission Upgrades: From Frustration to Function

The manual transmission (yes, it’s a rare NV5600 6-speed manual) had issues from the start. It wasn’t shifting correctly, and we quickly discovered the “rebuilt” transmission needed a full teardown.

We rebuilt it properly and added a South Bend dual-disc organic clutch for smooth, strong engagement that’s still daily-drivable. We also replaced the factory two-piece driveline with a one-piece aluminum driveshaft—a huge reliability upgrade.

Diesel Tuning and Street Performance

We used MM3 tuning from Calibrated Power, and they nailed the tune. The result? A Cummins-powered beast that runs smooth, pulls hard, and is still tame enough to drive every day.

Suspension & EGT Fixes

This lifted Dodge Ram 2500 sits on 37-inch tires and wide wheels, so we addressed suspension tuning next. We also had to tame high EGTs (Exhaust Gas Temperatures)—despite a larger intercooler setup.

So, we pivoted:
- Switched to 15% over diesel injectors
- Dropped to a 64mm turbo for better cooling and drivability

The tradeoff was worth it: cooler temps, smoother power delivery, and a more usable powerband.

Why This Truck Matters

We’re building this truck not just for fun, but to showcase diesel parts and upgrades we believe in. Every component is one we confidently recommend to customers who care about performance, drivability, and durability.

This isn’t the wildest build on YouTube—but it’s the kind of Cummins truck build you can trust. It’s tough. It’s fun. And it’s built to go the distance.

Join the Build Journey

We’re documenting the full journey of this 2005 Dodge Ram 2500 Cummins build on YouTube and Instagram. Whether you’re planning a similar diesel performance upgrade, or just dreaming about your next truck, we’d love to have you along for the ride.

— The Deer Park Diesel Team

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🎥 Shop Truck Build Ep. 2: The Heart of the Beast! 😈