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GMC Duramax HD Sport Truck

Three to One

Chris Tobin
Apr 8, 2019
Photographers: Chris Tobin
Twenty-one-year-old Brett Young had the good fortune of growing up in a family of gearheads, surrounded by their various street rods, hot rods, muscle cars, and sport trucks. The young diesel mechanic has owned many cars and trucks himself, most of which had oil-burners under the hood. While attending University of Northern Ohio in 2016, he happened upon a totaled ’05 GMC Sierra 2500HD that had a bad encounter with a large tree.
Rather than shying away from the wrecked truck as many would have, the intrepid builder opted to trade his running and driving ’97 Dodge Ram 2500 for the totaled regular cab that in two years would become the truck of his dreams, thanks to hard work and the help of his family and many friends.
The build started with Brett focusing on the Sierra’s frame and chassis, making sure everything was not only straight but also in better-than-new condition. The frame actually turned out to be too twisted to bend back into shape, so he purchased an ’04 GM ¾-ton chassis and went to work.
Photo 2/35   |   Brett Young’s ultra-custom ’03-to-’05 GMC Sierra 2500HD was built with a street rodder’s attitude and diesel power under the hood.
The entire frame was stripped and painted, and the suspension components that were being reused were powdercoated. In addition to refinished original and new components, Brett upgraded the steering and suspension with Moog steering components and Bilstein 5100 series shocks on all four corners of the rig. He also wanted to set the proper stage for his street-rod–inspired sport truck, so he opted to turn down the front torsion bars to net a 4-inch reduction in ride height and installed a Belltech 6-inch lowering kit in the rear that relocates the spring hangers to allow the truck to sit low but still be able to tow with no problem.
With the chassis complete, Brett turned his attention to the body and enlisted the help of friends Tim Clingman and Duane Howard. Shortly after getting started on the totaled cab, they realized it was bent beyond repair, so Brett found a clean ’03 regular-cab Sierra 2500HD to merge with his chassis. The trio straightened each body panel to better-than-new condition with countless hours of blocking and sanding before Tim and Brett laid on several coats of DuPont Black Cherry paint, with a custom tint to give it that warm “root beer” tone in bright light.
Their attention to detail is evident in the flawless finish. This team worked diligently to coat every surface of the truck, including under the hood, inside the bed, and on all the jambs and inner panels.
Photo 3/35   |   Brett’s rig sports a clean look, with just enough chrome and brightwork to set off the Black Cherry Metallic paint. The bulge of a cowl-induction hood subtly betrays the fact that a potent 6.6L Duramax LLY powerplant lurks below the silky-smooth surface.
After reworking the truck’s ’04 chassis and ’03 body, Brett turned his attention to the powertrain, opting to go with the original 6.6L Duramax LLY engine from the totaled ’05 Sierra. The cylinder heads were given a precision valve job before being reinstalled on the original short-block with new gaskets and ARP studs.
Fueling chores are handled by an AirDog 4G 165-gph lift pump and filter system that is installed under the bed. The combo feeds a pair of stock Duramax LBZ CP3 injection pumps mounted on the engine by a PPE Dual Fueler kit. The high-pressure fuel is then received by a set of 250-percent-over S&S Diesel Motorsport injectors. Engine controls are handled by the stock ECM loaded with EFILive calibrations created by 503 Diesel Performance.
Wanting to keep the engine bay clean, Brett polished, painted, or powdercoated most of the accessories and components, including the air-conditioning system’s compressor and lines, and the thermostat housing, boost tubes, Vibrant HD clamps, and turbocharger are all polished to a brilliant finish. Speaking of turbo, Brett kept things simple by going with a single—but big—BorgWarner S472 SX-E .90 ’charger that’s perched in the factory location in the valley.
Photo 4/35   |   The great-looking Duramax was built from a street-rodder’s perspective, as evidenced by polished and powdercoated lines, tubes, accessories, and the bright-shining turbocharger, of course.
Photo 5/35   |   The BorgWarner S472 SX-E turbo draws in air directly from the atmosphere (Brett was unable to fabricate an intake and filter in time for our photo shoot). Pressurized boost is channeled to the intercooler through a polished aluminum tube that connects directly to the outlet with a Vibrant HD clamp for a positive seal.
Photo 6/35   |   Another polished tube sends the intake charge from the ’cooler into the intake runners. Notice the polished lines of the air-conditioning system. It’s this attention to detail that really dresses up the engine bay.
The boosted intake charge from the turbo passes through the stock GM intercooler before being channeled back into the engine. Duramax LBZ intake manifolds are used for optimum airflow into the cylinder heads, and the engine exhales spent exhaust gases through a pair of ATS Diesel Performance exhaust manifolds, up-pipes, and a fully polished Diamond Eye Performance stainless steel exhaust system. Brett estimates the engine makes around 767 hp and 1,220 lb-ft of torque based on other similar builds he has worked with.
The engine is backed by an ’05 Allison 1000 six-speed automatic transmission Brett and Kevin Leichliter rebuilt with SunCoast Diesel Transmissions internals (the gearbox is painted gray to contrast the truck’s black chassis and Black Cherry exterior color). They also installed Merchant Automotive’s Pump Rub Elimination kit in the transfer case. The Allison is linked to the engine by a billet flexplate and torque converter from ATS and Goerend Transmission.
Finishing the interior and outfitting the Sierra with flashy rolling stock were the final pieces of Brett’s elaborate puzzle. The footwear package is comprised of 22x12 polished Weld Racing XT Vektor wheels wrapped by 325/40R22 Hankook Ventus ST tires for confident grip on the road and good looks, too.
Photo 7/35   |   Combined with the lowered stance, 22x12 Weld Racing XT Vektor wheels wrapped in 325/40R22 Hankook Ventus ST tires fill the wheelwells on all four corners. If you look closely, you can see the drilled and slotted Power Stop brake rotors Brett installed to help whoa down the beast.
The interior proved to be a little more challenging, as Brett wanted the truck to have a street-rod persona. He turned to Dennis and Shane Gamble at Sew What Upholstery in Dayton, Ohio, to install the custom cinnamon leather upholstery throughout the cabin. Some stock panels and the seats were reupholstered while the dash was reworked and then covered in the rich brown leather. Brett also installed a Kenwood double-DIN audio/visual receiver in the dash and Kicker speakers to make road trips more enjoyable. A pair of AutoMeter Competition Instruments gauges is installed in the modified Cadillac Escalade center console, allowing Brett to keep an eye on engine activity.
More than two years of blood, sweat, and tears and a rash of parts from three different model years combined to make a stunning street-rod–inspired sport truck that turns heads everywhere it goes. The truck was just finished before the 2018 Scheid Diesel Extravaganza, where Brett unveiled it to the world. At that show, it took home the Best GM award—and at other shows since Scheid—proving the hard work and dedication is paying off.
Photo 8/35   |   The turbo’s downpipe is dressed in high-heat header wrap to help keep underhood temperature down and protect the custom paint.
Photo 9/35   |   Plenty of Number 2 diesel is fed to S&S Diesel Motorsport 250-percent-over injectors thanks to AirDog’s 4G 165-gph lift pump and a PPE Dual Fueler setup with a pair of CP3 injection pumps providing the high-pressure fuel.
Photo 10/35   |   Gmc Duramax Hd Sport Truck Engine Alt Ac
Photo 11/35   |   Gmc Duramax Hd Sport Truck Hood
Photo 12/35   |   Looking at Brett’s GMC from the front, it’s easy to see the additional work he and his team put into the truck, including reworking the front bumper mounts to eliminate the unsightly gap and filler piece employed by the factory. The GrillCraft polished stainless steel grille insert looks great in the chrome shell while a “Duramax Diesel” fender badge is installed to give a not-so-subtle nod to the stout powerplant lurking behind the grille.
Photo 13/35   |   Taking a peek under the truck makes it clear how this four-wheel-drive monster gets its lowered stance. To achieve the 4-inch drop, Brett cranked the front torsion bars down, replacing and/or rebuilding the rest of the suspension with GM, Moog, and Bilstein components.
Photo 14/35   |   To help fit the sport-truck mold with his ¾-ton bruiser, Brett replaced the factory antenna mast with this shorty mast. Who actually listens to the radio anymore anyway?
Photo 15/35   |   While painting the exterior trim, door handles, and mirrors is a common practice, seeing it done this well is a rare treat!
Photo 16/35   |   Opening the doors reveals the high level of street-rod influence that helped shape the theme of Brett’s build. The custom cinnamon leather interior uses a mix of reupholstered stock components, as well as totally custom pieces that are integrated into the mix.
Photo 17/35   |   Gmc Duramax Hd Sport Truck Interior
Photo 18/35   |   Matching suede covers the stock headliner, enveloping the interior in a warm cinnamon glow.
Photo 19/35   |   The Sierra’s GM bucket seats are covered with buttery-soft cinnamon leather in a slick, diamond-stitch pattern. They are divided by a full-length Cadillac Escalade center console that is also wrapped in cinnamon leather to match the rest of the interior.
Photo 20/35   |   To keep an eye on boost pressure and exhaust gas temperature, Brett installed a pair of AutoMeter Competition Instruments gauges in the front portion of the center console. Then, to make cruising more enjoyable, he installed a double-DIN Kenwood receiver in the stock dash location to power Kicker speakers installed in the doors.
Photo 21/35   |   The custom-molded dash top integrates stainless steel mesh panels to replace the typical plastic defroster grille vents.
Photo 22/35   |   With a 4-inch drop up front and 6-inch drop in the rear, Brett’s GMC has a near-perfect stance, ready to blast off the line or charge hard into the next turn.
Photo 23/35   |   The rebuilt Allison 1000 six-speed automatic transmission and transfer case both sport fresh coats of paint to match the powdercoated driveshaft. To help keep the fluid temperature down while the gearbox is working hard, Brett installed a deep-sump Mag-Hytec pan for additional cooling and capacity.
Photo 24/35   |   From the front side of the rear axle assembly, you can see the polished stainless steel Diamond Eye Performance exhaust system; powdercoated driveshaft, lift pump, and filter system; painted chassis, and Bilstein shocks…
Photo 25/35   |   …and then from the rear, Mag-Hytec’s differential cover is visible, as well as the exhaust exiting in the stock location. If you look closely enough, you might even see a hidden hitch tucked against the frame behind the rear roll pan.
Photo 26/35   |   With the stock bumper replaced by a painted roll pan and smoked Recon LED tail and third brake lights, Brett’s Sierra looks good from any angle.
Photo 27/35   |   A Lund folding tonneau cover gives the truck’s bed a finished look while providing Brett a place to stash his cleaning and polishing supplies when the rig is on display at events.
Photo 28/35   |   Folding back the tonneau cover reveals the bed in all its painted, buffed, and polished glory. While many others might have taken the easy route with a bedliner of some type, Brett didn’t take any shortcuts in his build.

Fast Facts:

Year/Make/Model: ’03-to-’05 GMC Sierra 2500HD
Owner: Brett Young
Hometown: Fairborn, Ohio
Odometer: 153,000 miles
Engine: ’05 6.6L Duramax LLY V-8, stock cylinder heads, valve job, ARP head studs
Programming: EFILive with tuning by 503 Diesel Performance
Fuel: AirDog 4G 165-gph lift pump, 250-percent-over S&S Diesel Motorsport injectors, PPE Dual Fueler, Duramax LBZ CP3 injection pumps
Air: BorgWarner S472 SX-E .90 turbocharger, aluminum boost tubes, Vibrant locking connectors, GM intercooler, Duramax LBZ intake manifolds
Exhaust: ATS Diesel Performance manifolds, Diamond Eye Performance 5-inch stainless steel tubing
Transmission: ’05 Allison 1000 six-speed automatic, SunCoast Diesel Transmission clutches, Goerend Transmissions torque converter, ATS Diesel Performance billet flexplate, 6.0L Ford Power Stroke transmission cooler, Mag-Hytec deep-sump pan
Horsepower: 767 hp (est.)
Torque: 1,220 lb-ft (est.)
Tires: 325/40R22 Hankook Ventus ST
Wheels: 22x12 Weld Racing XT Vektor
Suspension: Bilstein 5100 series shocks (front and rear), powdercoated stock components, turned-down torsion-bar keys, lowered 4 inches (front), Belltech leafspring-hanger relocation kit, lowered 6 inches (rear)
Axles: Stock IFS with 3.73 gears (front), AAM rear-axle assembly, 3.73 gears, Mag-Hytec differential cover
Body: ’03 GMC Sierra 2500HD cab, custom-tinted Black Cherry Metallic paint, steel cowl-induction hood, paint-matched mirrors, door-and-tailgate handles, fender flares, steel rear roll pan, debadged, smoked Recon LED taillights, front bumper lifted to fill factory gap to grille surround, GrillCraft stainless steel grille insert
Interior: Custom cinnamon leather upholstery, Cadillac Escalade dash and center console, AutoMeter Competition Instruments boost pressure and pyrometer gauges, billet aluminum leather-wrapped steering wheel, Kenwood audio/visual receiver, Kicker speakers, custom carpet
Fun Fact: Brett is a true gearhead, from a family of hot-rodders with an amazing collection of muscle cars and trucks. One of the next family projects will be swapping a 6.6L Duramax engine and ZF6 six-speed manual transmission into Tom “Papa” Young's slammed ’87 Chevy C-30 dualie. It will definitely be a truck to look out for as the Young family continues to crank out amazing builds!

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