BEAST MODE | A 12-Valve ’49 Power Wagon on 39’s

Mike McGlothlin . December 16, 2021 . All Feature Vehicles

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What happens when you treat the baddest 1-ton 4×4 of all time to a 12-valve Cummins swap, Dana 60 and 14-bolt axles, and completely modernize the cab? You get this one-of-a-kind ’49 Dodge Power Wagon owned by Carl Van Rooy. Turning to friend, fabricator, and off-road specialist John Conrad of J.B.’s 4×4, the project took root, got underway, and was ready for delivery 13 months later. In Conrad’s care, he and his crew made the war-born Power Wagon much more than the tractor it essentially was when it left Chrysler’s Warren, Michigan assembly line some 70 years ago.

While Carl wasn’t necessarily after building a powerhouse, he did have the folks at J.B.’s 4×4 turn up the Cummins’ wick a bit, in the form of a few P-pump tweaks. A bump in timing, higher rpm governor springs, and a custom grind fuel plate increased the P7100’s fueling capabilities, and it feeds a set of remanufactured, stock-spec injectors with fresh nozzles. Combined with the turbo upgrade that was made, the Power Wagon is likely capable of at least 350-rwhp and 700 lb-ft of torque.

A BorgWarner S300 sits in place of the original Holset HX35W along the exhaust manifold, this SX-E version sporting a forged-milled compressor wheel with a 63mm inducer and a 68mm turbine. The 3-inch, heat-wrapped downpipe just clears the firewall, and all intake and intercooler piping was built in-house at J.B.’s 4×4.

It just fits under the butterfly hood of Carl Van Rooy’s ’49 Dodge Power Wagon, but the 5.9L Cummins is lightyears ahead of the 94hp 230ci flathead I-6 it originally came with. The ’96 model year 12-valve donor was cracked open and refreshed prior to the build, receiving all-new bearings, seals, and a brand-new cylinder head, complete with 60-lb valve springs. The air cleaner assembly is a Unique Metal Products piece, while the expansion tank you see here works in conjunction with the custom radiator, both of which were fabricated by J.B.’s 4×4 in Kingman, Indiana.

Restoration & Repower

The cab-off restoration, powertrain swap, and drivetrain upgrades all took place at Conrad’s Kingman, Indiana facility, with most outsourced work on select components and pieces primarily being performed at local businesses. The Power Wagon’s original frame was powdercoated and modified to accommodate repositioned motor, transmission, and fuel tank mounts, along with relocated leaf spring brackets. PPG provided the base paint that’s about as close to the old Ponchartrain Green as they come.

With its roots running deep in the off-road world, the guys at J.B.’s swapped an open differential Dana 60 in place up front, along with some serious steering upgrades. A custom pitman arm and steering system with PSC cylinder-assist was built, the steering box was relocated and fitted with a high steer arm, and a heavy-duty tie rod assembly was added as well.

An AirDog fuel supply system mounted along the driver side frame pulls diesel from a custom 35-gallon fuel tank that was fabricated by J.B.’s 4×4. The traction bars, also pieced together at J.B.’s, keep the rear 14-bolt from wrapping and the leaf springs from twisting.

The 14-bolt GM out back conceals a 3.73 ring and pinion and a Detroit Truetrac limited slip differential, both of which sit behind a fabricated diff cover. Its axleshafts are stock and it’s also been converted to employ disc brakes.

Making The Cummins Fit

Well known for their ability to convert classic off-road rigs to 6BT or even 4BT power, the guys at J.B.’s 4×4 were definitely up to the task of making a 5.9L fit in the Power Wagon’s narrow engine bay. A set of modified second-gen motor mounts solved the positioning of the Cummins easy enough, but its front-to-back length was the real worry. Stacking all the heat exchangers behind the grille and not having to push the Cummins through the firewall in order to accommodate everything was where Conrad and his crew were most resourceful. The radiator issue was solved by fabricating an aluminum unit in-house, along with an expansion tank which was mounted above the number one cylinder (and between the air intake and cold-side plumbing). Bell Intercoolers supplied the compact air-to-air intercooler that keeps the 12-valve’s EGT in check. An air cleaner from Unique Metal Products also makes for good use of space near the firewall.

Keeping the 5.9L in its power band is a 47RE automatic, prepped at J.B.’s 4×4. Power transfer begins with a Stage 5 triple-disc, billet front cover torque converter from RevMax. Extra fluid capacity checks in in the form of a Mag-Hytec deep pan and an auxiliary B&M transmission cooler ensures the four-speed never sees excessive heat. The 47RE is tethered to an NP205 transfer case.

Saying the Power Wagon’s interior has been modernized would be an understatement. It’s even been treated to weather stripping—something Power Wagon’s were void of back in the day. The floor pan, gauge panel, center console, drink holder, and electric window switch panels were all built by J.B.’s 4×4. Wise Guys Seats & Accessories supplied the 6-way electric power adjustable seats while nearby Don’s Auto Trim handled the upholstery. A Lokar Performance Products shifter is tied in with the 47RE automatic transmission.

That’s right, it’s got cruise control (thanks to a Painless wiring harness). And not only that, Carl can keep tabs on engine rpm, oil pressure, voltage, fuel, water temp, speed, boost, and EGT courtesy of Dakota Digital gauges. The wood grain work in the interior was performed by Indy Paint Shop in Brownsburg, Indiana, the steering column is an Ididit piece, and the steering wheel itself came from MOMO. Also notice the air vent, which is part of the Power Wagon’s Old Air Product air condition system.

Fresh 5.9L

Starting with a 470,000-mile running donor, the ’96 model year Cummins was torn down for a full-on refresh. The block checked out OK but a crack in the head was all the convincing needed to source a brand-new one, complete with 60-lb valve springs, from Phil’s Automotive Machine Shop in Danville, Illinois. From there, six new stock replacement pistons from Mahle went in, along with fresh bearings, seals, and gaskets from top to bottom. The engine’s fuel system was also renewed thanks to six remanufactured injectors and the P7100 being treated to a considerable advancement in timing, a custom grind fuel plate, and higher rpm governor springs. A 63mm S300 SX-E turbo from BorgWarner handles boost production and spins to life quickly.

The Power Wagon’s one-off exhaust system culminates in a baffled stack with heat-shield mounted along the passenger side running board, which had to be made into a two-piece step in order to accommodate it. The spare tire carrier was also modified to accept the 39-inch BFGoodrich mud terrain you see here.

Relocating the leaf spring brackets on the frame provided for a pair of first-gen Dodge leaf packs to be run up front. In the rear, factory Dodge two-wheel drive hangers are present. At each corner of the Power Wagon, you’ll find a 5100 series Bilstein shock absorber.

Beneath the era-appropriate wood bed floor, a lot is happening. Here, you can see one of the custom length driveshafts built by Patterson Driveshaft, the battery trays that hold the Power Wagon’s yellow top Optima batteries, and part of the E-brake setup supplied by Moonshine Mafia Motorsports.

Built 47RE & NP205

Building a 47RE that would never flinch under the load of 700 lb-ft of torque and the strain of turning 39-inch mud terrains, the second-gen-derived four-speed was reinforced throughout, equipped with a RevMax Stage 5 triple-disc converter and high-pressure valve body, and topped off with a Mag-Hytec deep pan. An Anteater Classic STC transmission controller from Firepunk Diesel allowed the guys at J.B.’s 4×4 to dial in the automatic’s shift points, as well as its lockup and Overdrive strategies. Thanks to a first-gen donor, an NP205 transfer case is married to the 47RE, along with an E-brake assembly from Moonshine Mafia Motorsports. Custom length driveshafts from Patterson Driveshaft send power to the front and rear axles.

Much of the Power Wagon’s go-anywhere attitude stems from the 39×13.50R17 BFGoodrich Mud Terrain KM3’s it rides on. But to be sure, the aluminum 17×10 TR Beadlock wheels mean business, too.

All of the 47RE four-speed’s shift points and patterns (along with precise command of lockup) were dialed in through the use of Firepunk Diesel’s Anteater stand-alone transmission controller. The Anteater module was mounted inside the glove box, beneath a USB port and a Hobbs hour meter for the engine.

Dodge Dana 60, GM 14-Bolt

Axle selection boiled down to the tried and true Dana 60 up front and a GM 14-bolt in the rear. Both make use of a 3.73 ring and pinion, but the 14-bolt was treated to a Detroit Truetrac differential, with its axle tubes serving as mounting points for the traction bars that link the axle to the frame. The Dana 60 sits below first-gen intended leaf springs and features a host of steering upgrades. The steering box was relocated and fitted with a high steer arm, a custom pitman arm and PSC cylinder-assist components were added, and a heavy-duty tie rod assembly also made the cut.

The front and rear bumpers are J.B.’s 4×4 pieces, with the rear unit even incorporating the Power Wagon’s receiver hitch (yes, Carl plans to do a bit of bumper towing with it). The front bumper accommodates a 12,000-pound M12 winch from Warn through the use of custom-tailored winch brackets.

The Ultimate Power Wagon

The original Power Wagon was known for its simplicity, durability, hauling capability, and off-road readiness, but Carl’s takes things several steps further. The rebuilt P-pumped 5.9L Cummins and reinforced 47RE bring million-mile durability to the table. The Dana 60, Truetrac-equipped 14-bolt, 39-inch BFGoodrich Mud Terrains, and 12,000-pound Warn winch provide endless off-road capability. And finally, the show-quality frame, body, and bed restoration—along with the completely refinished and updated interior—make it one of the finest classic repowers we’ve ever come across.