A Show-Stopping, Cummins Cab-Over Conversion—Built For Work And Play
Greg Noble has a classic car, John Deere tractor, and motorcycle collection that would be the envy of any collector that accumulates either of those things, so why build a cab-over GMC with a 12-valve Cummins in it? Turns out, when you own multiple farms, bear an affinity for old GM’s, and have a bunch of wild ideas running through your head, you can easily justify the need for a one-of-a-kind vehicle. And after enlisting the help of friend Cale Kern, one of the premiere hot-rod builders in the Midwest, there was no stopping the Orleans, Indiana resident’s plans to build a one-of-one ’47 GMC COE.
To say that Greg was fired up to get the project underway was an understatement. He even secured four different COE makes from the same era to choose from. And although it was determined that a Duramax would fit in the ’53 Chevy he’d hauled home, the inline architecture of the 5.9L proved a better fit for his ’47 GMC, a clean find from Kansas. Its original frame was in great shape and the patina’d body was perfect for a guy who’s big on original paint. So with the truck decided on, it was time to find an engine.
After dropping a core 12-valve block off at Scheid Diesel, the folks there pieced together a long-block more than capable of handling a little abuse. The 5.9L benefits from ARP main and head studs, ARP bolts in the factory rods, Mahle cast-aluminum pistons and bearings, a Scheid street cam, and a fire-ringed head equipped with 60-lb valve springs. Other aftermarket parts included a billet-aluminum front cover, tappet cover, and intake plate, along with a Fluidampr. A Fleece coolant bypass system keeps cylinder temps in check across the board.
Engine And Turbo Fitment
In the words of Andy Thomas, owner of Southern Indiana Diesel Service who contributed many hours to the build, “the engine compartment is ten times tighter than it looks.” Among many things, careful consideration had to be given to turbo location, intercooler piping, and the injection lines. The .093 stainless lines had to be custom bent by Scheid in order to clear the floorboard of the cab, even spanning between the BD individual valve covers. For its low and rearward mounting position, a third-gen, motorhome-style Steed Speed exhaust manifold was chosen for mounting the turbo, an S362 with a T4 turbine inlet flange.
Arguably, there is not better old-school diesel combination than a 12-valve Cummins matched with an NV4500. The decision to go with a manual transmission was fitting for a truck that would see use around the farm, but its integration—particularly in the cab—wasn’t as straightforward as you might think. First, the shifter wouldn’t clear the back of the cab. And then the original parking brake lever couldn’t be retained due to contacting the passenger seat. These problems were solved by turning the shifter around and by switching to an E-Stopp (electric) parking brake. Southern Indiana Diesel Service furnished the rebuilt gearbox, which is graced with a larger, 1-3/8-inch diameter input shaft and a quiet street dual disc clutch from Valair.
Full air ride offers both a stable feel when loaded and comfort when cruising. It’s made possible in the rear thanks to an HD four-link system from Ridetech, which incorporates air springs rearward of the narrowed axle. Custom-fabricated lower control arms provide the mounting point for the Firestone bags up front, and the rack and pinion out of a Dodge Sprinter helped modernize the truck’s steering. A bit of resourceful engineering on the part of Cale Kern Hot Rods makes it possible for the truck to still be driven in the event of air spring (or an air spring system) failure.
Other than the black, milled-down, 22×8.25-inch Alcoas proving a perfect fit for the truck, aesthetically, the real automotive creativity lies in the bed. Starting with a sketch Cale Kern put together, the 7-foot-wide piece mixes the look and functionality of a flatbed with a wrecker bed. The bead-rolled bedsides were seamlessly matched with the patina on the cab courtesy of patina master, Jerome Borris, which to the layperson makes the bed appear original. The bed is also furnished with a gooseneck ball, a cargo box at the back of the cab, and an aluminum fuel tank on the driver side that is matched with a storage box on the passenger side which contains the batteries and onboard air compressor.
Even with COE’s making a comeback in recent years, Greg’s GMC stands apart from the crowd. Whether it’s the original paint, the semi wheels, the era-appropriate yet custom bed, or the distinctive clatter coming from the engine compartment, his cab-over creation commands the undivided attention of everyone within sight or earshot. And while the no-expense-spared nature of the build makes it what it is, so does its retention of the 75-year-old cab and frame. Better yet, throughout the course of the build Greg kept it all in the family, so to speak. Cale Kern Hot Rods, Southern Indiana Diesel Service, Ridetech, Dually Kings, and Scheid Diesel all make their home in Indiana just as Greg does—and each played an indispensable role in the project. We think it’s safe to say that Greg’s ’47 GMC—with its skillful blend of old and new—fits right in with his classic car collection.
“Even with COE’s making a comeback in recent years, Greg’s GMC stands apart from the crowd.”