65 F-600 Diesel Revival: Cummins Power and Second-Gen

Resurrecting a Classic: A 1965 F-600 Reborn with Cummins Power

This ’65 F-600 Was Reborn With A Second-Gen Chassis And Cummins Power

Sentimental value drives some of the most unique builds you’ll come across in the diesel world, and a sentimental attachment was the genesis behind Cory Wheat’s idea to resurrect his late grandfather’s old grain truck. With a knack for building medium-duty rat-rods, a flood of ideas went into this ’65 F-600 project. The body would be placed on a ‘97 Dodge chassis and a second-gen powertrain that included a 12-valve Cummins and the venerable NV4500 transmission. The original grain bed would be removed and repurposed to create a skirted flat bed. Then a set of milled-down super singles would help Cory stuff 37-inch rubber inside the large fender wells.

No, it’s not some piece of old-iron rotting away in the weeds, it’s a ’65 body F-600 sitting on a ’97 Dodge Ram 2500 frame, axles, and suspension—and it runs great. The renewed lettering on the patina’d doors helps pay homage to the truck’s previous owner, Cory Wheat’s grandfather, and the 6-inch hood stack just seems to fit.

No cutting of the firewall was required to drop the B series Cummins into place, but it did crowd things a bit up in front of it. Though the factory Dodge radiator was reused, there was no room left over for the factory fan, shroud, or intercooler. Cory resolved these issues with electric fans, fabricating his own shroud, and installing a compact intercooler behind the front bumper.

21,000 Original Miles

Originally purchased by Sinclair Oil Corporation, the F-600 was obtained by Cory’s grandfather, Jerry Plummer, in 1968. Promptly turning it into a grain hauler, it was placed on active duty at the family-owned Sugarwood Farms and served many years there, racking up most of its 21,000 miles during the annual corn and soybean harvest. When Cory decided to resurrect the old grain truck in 2021, he was adamant that the patina’d cab and front clip would remain original pieces—but he made it a point to have the lettering on both doors redone. Then it was time to update the truck’s foundation.

Being that the Cummins came from a ’97 model year Dodge with a manual transmission meant that Cory’s 5.9L benefitted from the desirable, 215 hp P-pump. Although nothing has been altered on the P7100 to his knowledge, a timing bump and several free tweaks could easily add an additional 100hp to the F-600’s bottom line. Fuel supply for the P-pump is cut off old-school-style, via cable, when it’s time to shut the truck down.

The factory, tough-as-nails Holset HX35W hangs from the stock exhaust manifold, its wastegate long ago having been disabled to allow for more boost. The intake system consists of an open element air filter. The extent of the exhaust system includes a fabricated and then heat-wrapped 4-inch diameter downpipe, which transitions into an angle-cut, 6-inch stack in the truck’s hood.

Second-Gen Frame, Suspension, And Axles

For a proven, modern day chassis, second-gen running gear was rolled into place beneath the hovering cab. The frame, suspension, and axles were all sourced from a ’97 -ton Dodge donor, and since the second-gen had been four-wheel drive it meant a Dana 60 was part of the deal, complete with coil springs and upper and lower control arms. The leaf spring rear axle is a 3.73-geared Dana 70. Surprisingly, the body fit over the second-gen’s frame rails just fine. It was the fender wells that concerned Cory most. Specifically, he went to great lengths to ensure the front clip mounted in a fashion that allowed the 22-inch super singles to be perfected centered in the fender wells.

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When you have an NV4500 at your disposal, you don’t try to reinvent the wheel. Sticking with the familiar pieces you’ll find in many ’94-’98 4×4 Rams, the NV4500, connected to the venerable NP241 transfer case, is present within the second-gen chassis under Cory’s F-600. So far, the five-speed is yet to need a clutch upgrade.

Another familiar item for a second-gen Dodge is the Dana 70, which is now parked under the rear of the F-600. It’s been fitted with 3.73 gears but is otherwise untouched. It might not be the holy grail Dana 80, but the 10.54-inch ring gear Dana 70 shouldn’t have any issues with Cory’s roughly 300 hp, 600 lb-ft power recipe.

As you would expect, the second-gen front coil spring suspension, complete with upper and lower control arms, is along for the ride, too. Like the Dana 70 out back, the Dana 60 up here has been equipped with 3.73 gears but other than that is all stock. As you can imagine, the coil spring, Dana 60’s ride quality is much improved over the original I-bream, leaf spring arrangement.

Way Better Than A 300 CID Gasser

Matching the rugged exterior look of the medium duty Ford is a 400,000-mile, P-pumped 12-valve 5.9L Cummins that keeps chugging along. As far as fitment was concerned, no cutting of the F-600’s firewall had to take place. However, it was a different story up front. By retaining the ’97 engine’s OEM radiator, Cory ran out of room to accommodate the factory fan and fan shroud. Improvising, he installed electric fans along with a homebuilt shroud. And because of the lack of real estate behind the grille Cory was also forced to change the intercooler, as well as its location. A unit that measures smaller than stock was sourced online and mounted behind the front bumper. The Holset HX35W’s wastegate has been disabled to allow for plenty of boost.

If Cory can’t build it himself he usually sources it secondhand or from the junkyard. In this case, Facebook Marketplace gifted him with the super single wheels that are now bolted to the F-600. Milled down to 22’s courtesy of his cousin and then powder coated black, they blend right in with the truck’s surface rust look. For tread, Cory went with Nitto Ridge Grapplers that measure 37×12.50R22. Their high load index (3,860 lbs at 80 psi, per tire) suits the truck well when towing.

Instead of scrapping the F-600’s grain bed completely, Cory reincorporated it into the flat bed. The original bed sides were repurposed as skirting, helping to give the truck the western-hauler type appearance Cory was after. Here you can see also how well the 37-inch dual Ridge Grapplers fill the wheel openings.

On the F-600’s back glass you’ll find a little self-promotion. Cory and his wife, Hannah, operate Cory Wheat Customs, a small Indiana shop that builds one-off vehicles, most of them diesel-powered, and brings viewers along for the ride by way of their YouTube channel. In less than two years, the channel has grown to 29,000 subscribers.

NV4500 And 4×4

With the truck’s primary purpose being a work truck, it only made sense to keep things simple with a manual transmission. And although the original F-600 came equipped with a standard shift, it was never four-wheel drive. Cory changed that thanks to utilizing the second-gen powertrain he had at his disposal, which included an NP241 transfer case being bolted to the tried and true NV4500. The extent of the integration work for the five-speed included transmission tunnel work in order to retain the shifter. For now, the factory-spec clutch has yet to slip—even with a loaded trailer coupled to the gooseneck ball in the bed.

In the cab, nearly everything is original other than the aforementioned NV4500 shifter, an aftermarket analog gauge, and these upfitter switches from Rough Country. They’re integrated with a multi-light controller that’s used to operate the electric fans, the headlights, and the truck’s trail lights.

Grain Truck-Turned Tow Rig

More than half a century after it left the assembly line, Cory’s F-600 arguably sees more action now than it ever did back in the day. Thanks in large part to the second-gen chassis and Cummins conversion, it’s gone from hauling grain to hauling new projects home—more old iron that Cory can outfit with diesel propulsion at his shop, Cory Wheat Customs. All told, the project took him just 72 days (and nights) to complete, a reflection of both his youth and work ethic. So are medium-duty Cummins conversions the next big thing? It wouldn’t disappoint us. Afterall, in addition to being a great tribute to his grandfather, Cory’s four-wheel drive F-600 has “beast mode” written all over it.