As A Cummins-Powered ’51 Chevrolet

You see them all the time, especially during planting and harvest season. The service trucks that show up in the field to keep equipment running are the backbone of any farming operation. When he didn’t like the prices he was seeing while shopping for the family farm’s new service truck, Chris Ohl decided to take matters into his own hands with an old Chevy truck. He would build it himself—and it would be one of a kind. After all, his great grandpa’s ’51 old school Chevrolet 3800, a 30,000-mile 1-ton grain truck that’d been parked for a number of years, was practically begging to be transformed into a service rig.

Well-Preserved Patina

1951 Chevrolet 3800 1-ton Cummins powered grain truck conversion

Combining his wrenching, welding and auto body skills with the knowledge he’d amassed in other encounters with the 12-valve Cummins, Chris set out on what would become a year-long journey to bring the old Chevy back to life. A quick trip to Ohio yielded the second-gen Dodge chassis and axles he would set the ’51 cab on top of, along with the P-pumped 5.9L that would power the truck. Aside from having to address a rusted driver side cab corner and fender, the body was straight as an arrow and in what Chris believes was good-to-excellent condition, given its age. All of the new sheet metal and welds were left raw, and with no clear coat to speak of, Chris keeps the Patina preserved and protected with Gibbs penetrating oil.

A Tight Fit

Plucked from the same ’94 second-gen that would also donate its chassis for the build, Chris Ohl let Scheid Diesel crack open the 175,000- mile 12-valve 5.9L Cummins and start fresh from oil pan to intake. In Scheid’s care, the block was cut to accept fire-rings, while the stock connecting rods were equipped with ARP rod bolts and factory compression, cast-aluminum Mahle pistons. Valvetrain upgrades included one of Scheid’s drop-in street cams, chromoly pushrods, and stiffer valve springs. The remanufactured head fastens to the block via ARP studs while a one-piece valve cover and billet-aluminum intake plate from Scheid add a bit of bling.

Other than things being a bit tight under the hood, no notching of the firewall was necessary to accommodate the Cummins. In fact, the engine would be set back 4-inches on the frame after setting the cab on a pair of fresh cab mounts, which also called for repositioning the motor mounts. However, even with engine moved close to the firewall, little room remained for an adequately sized radiator. Instead of sacrificing cooling capacity, Chris purchased the largest off-the-shelf radiator Ron Davis builds and mounted it in the bed. Then to ensure the engine remained intercooled, he sourced a water-to-air unit from Precision Turbo, which sits suspended above the valve cover.

Scheid-Built 5.9L

As for the engine itself, Chris dropped it off at Scheid Diesel’s Effingham, Illinois location for a full refresh from the bottom up. The factory rods were retained but treated to ARP rod bolts and new, stock compression Mahle pistons. Scheid’s 12-valve street cam also made the build list, along with fire-ring grooves being added to the block for ultimate peace of mind. A remanufactured cylinder head fitted with stiffer valve springs is anchored to the crankcase via ARP 2000 head studs. A billet-aluminum, one-piece Scheid valve cover and intake plate top things off.

Space under the hood of a ’51 Chevrolet 3800 is pretty limited, especially when you’ve installed a much larger inline-six and prefer to run an intercooler. To get around his real-estate problem, Chris opted for Precision Turbo & Engine’s cast PT1001 water-to-air unit. Requiring engine coolant to operate, Chris built a separate cooling system dedicated to the intercooler using a Ron Davis radiator behind the grille and a Moroso water pump mounted along the frame rail.



Benched P-pump And An S300

Turning Scheid’s injection shop loose on the P-pump meant that it could easily support a 500-rwhp effort, should Chris want to take things that far. The benched 12mm P7100 was graced with 4,000-rpm governor springs, larger delivery valves, a rack cap, and lives at 18-degrees of timing. It sends fuel to a set of 5×13 injectors, also built by Scheid. A 58mm BorgWarner S300G turbo matches the engine’s fueling and produces 35-psi of boost before the wastegate opens.


Breathing through an AEM air filter and outerwear, the Scheid-sourced 58mm S300G was spec’d just about perfect for the engine’s fueling mods and sports a 64.5mm turbine wheel inside a .80 A/R exhaust housing. The internally wastegated charger allows roughly 35-psi of boost to be made at full tilt and is bolted to a T3 Steed Speed manifold and a 4-inch downpipe.

On the frame and just under the driver side door, Chris mounted an AirDog II fuel supply system. The lift pump sends a consistent 25 to 30-psi of diesel the P-pump’s way, and pulls fuel from a factory second-gen Dodge tank.


Splitting Gears

Like a lot of 12-valve swaps, Chris sided with the rugged NV4500 manual transmission to back up the 5.9L, but in this particular case there’s a twist. A Gear Vendors overdrive allows him to split gears, which with nine forward gear options makes the truck much more efficient when tasked with moving heavy loads. A single disc towing clutch from South Bend, along with a solid mass flywheel, dwells inside a Quick Time bellhousing and transfers power to the rear Dana 80 (and also the front Dana 60 when the NP241 is locked in four-wheel drive).

If you were thinking an automatic transmission didn’t belong in this truck, Chris would agree with you. A remanufactured NV4500 five-speed manual got the call, along with a Quick Time bellhousing, which conceals a South Bend clutch. A factory, second-gen NP241 transfer case handles four-wheel drive engagement.

Always In Service

Already having racked up several thousand miles on the finished product, Chris has held true to his original plans for the truck: to drive it and put it to work. During the farm’s busy season (primarily spring and fall), you can find his old Chevrolet out in the field, loaded up with a massive air compressor, welder generator, and 200-gallon fuel cell. Moving trailers and other equipment around is all in a day’s work, too. Chris tells us the truck pulls the farm’s 12,000-pound, bumper-tow seed tender with ease and, thanks to the Kelderman air spring system, rides like a newer service truck while doing it. Whether it’s off the beaten path and parked in a field or cruising down the highway, this reborn family heirloom will be turning heads for a long time to come.

A Gear Vendors overdrive unit allows Chris to split second through
fifth gears, effectively giving him nine gears to choose from. The added
gear ratios come in handy with a heavy load behind him, as they help
keep the Cummins in the meat of its power band.
The Dana 60 from the ’94 Ram donor was swapped under the old Chevy, but not before it was treated to a host of upgrades. Chromoly, 35-spline axleshafts were installed, along with an ARB air locker and a Mag-Hytec diff cover. Dynatrac heavy-duty ball joints, a heavyduty tie-rod and drag link kit, and a Red Head steering box also made their way into the mix, as well as a big brake kit with stainless brake lines, and the obvious 10-lug conversion.
After sourcing all the components himself, Chris built the beefy control arm arrangement up front. The linkages are fully adjustable and make use of greasable Johnny Joints from Currie Enterprises.
Like the Dana 60, the Dana 80 makes use of an ARB air locker, as well as a Mag-Hytec diff cover and a 4.10 ring and pinion—in addition to being converted to disc brakes. In between the rear frame rails, Chris mounted the air tank and air dryer that are part of the Kelderman air-ride system (which provides 6-inches of available height). A Fox 2.0 series shock exists at each corner, too.
When Chris ran out of room for the intercooler, he also made plans to relocate the radiator. Mounted behind the cab within the service bed, you’ll find the largest radiator Ron Davis makes, complete with dual 16-inch diameter SPAL fans. The fans, and virtually everything else that’s electronic on the truck, is controlled by an 8-circuit sPOD Bantam system. Also notice the 5-inch stacks. No service truck is complete without them, right?
In addition to the Kelderman system providing a level of ride comfort that rivals newer trucks, the Summit Racing-sourced TMI bench seat certainly does its part. The steering column is a TMI piece and so is the wheel, aside from an ididit adapter. As for the contraption at the top of the cab’s interior, that’s the Graham White manual train horn valve Chris uses to unleash the full audible fury of his Horn Blasters system.
Borrowed from one of the farm’s semis, Chris doesn’t have to reach very far to grab gears. The splitter switch, of which the signal is converted from air to electric in order to control the Gear Vendors unit, is located at the top of the shifter.
Aluminum service bed from Martin Truck Bodies
Don’t let the slick black look of the aluminum service bed from Martin Truck Bodies fool you, it’s chock full of tools year-round. And during harvest, Chris adds a few thousand extra pounds in the form of a skid he built with a 200-gallon fuel tank, a Miller welder generator, and everything else he needs. The BulletProof receiver hitch also sees use, with a trailer-mounted, 185-cfm air compressor tagging along any time big air is required, or the 12,000-pound seed tender needs moved. Also notice the 12,000-pound Warn Zeon winch protruding out of the bumper, and the vice mount… This thing is definitely ready for anything the field can throw at it.

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