SOS Styling, Modern Day Work Ethic

A Duramax and Allison-Swapped 4100 Series Chevrolet

It was supposed to just be a work truck, but for Phil Prinster—a man that’s made his old Oliver tractor so nice it no longer handles his brush-hogging duties—functionality alone wouldn’t suffice for his ’50 Chevrolet 4100. Once a part of the St. Louis metropolitan district fleet, the truck also served as both a milk and grain hauler for a period before Phil acquired it from a friend roughly three decades ago. For years, he never could quite decide what he wanted to do with the 1.5-ton Chevy, but then he got an idea.

Modernizing A Classic

Instead of doing a run-of-the-mill small-block build or dropping a big-block into the old truck, Phil decided a Duramax was the way to go. But rather than simply source an engine and transmission for the project, he picked up a wrecked ’06 Silverado 2500 and based everything on the HD’s modern era chassis, axles, and suspension. With help from his son Andy, son-in-law Josh, a host of local, small-town businesses, and the support of his wife of 41 years, Bonnie, Phil had the project wrapped up in a little over two years’ time.

For seamless integration, a Standalone Solutions wiring harness is employed, coming by way of nearby LinCo Diesel Performance. Also while in LinCo’s care, the engine was treated to a single EFI Live tune (a simple tow tune) from PPEI to help boost the LBZ’s bottom line. With the purchase of one of Airaid’s U-Build-It Master kits, Phil pieced together the engine’s cold air intake system himself.
The LBZ Duramax under the hood of Phil Prinster’s ’50 Chevrolet 4100 was robbed from a wrecked but rust-free ’06 2500 HD, along with the frame, axles, and suspension. Thanks to basing the project on the HD chassis, the ‘50’s firewall went untouched to accommodate the 6.6L. Locating and then mounting the radiator proved the most time-consuming part of the body swap.

Prior to sending the 4100 to his local auto body experts, Phil performed a bit of welding, filling holes on the exterior and along the firewall, as well as replacing both cab corners. From there, Outlaw Customz of Moscow Mills, Missouri took over. When it was time to paint the truck, it was sent over in pieces—first the MAR-K bed, followed by the cab, and then the front clip. The folks at Outlaw came up with the one-off paint color, too, which can only be described as being close to resembling a black cherry with a healthy amount of metal flake.

LBZ and Six-Speed Allison

Being that Phil wasn’t after making big horsepower with the project, the 200,000-mile LBZ Duramax and six-speed Allison were left untouched. As for the engine, it cleared the ’50 firewall by a mile but required the radiator be relocated. As for the Allison, raising the cab a couple extra inches above the frame helped Phil avoid any clearance issues. Nearby LinCo Diesel Performance helped ease the Duramax/Allison integration by installing a Standalone Solutions wiring harness, as well as a single EFI Live tow tune from PPEI to help wake up the LBZ. The factory ’06 transfer case, an NP261XHD, is still in the mix, too.

Though the HD frame had to be cut down to fit the length of the ’50 cab and bed, the front section was left alone. This includes the AAM 9.25 IFS, which exists just as it did when it left the factory back in ’06.
Also sourced from the ’06 donor was the six-speed Allison 1000. To avoid the task of having to massage the cab’s floor to accommodate the sizeable automatic, Phil lifted the cab away from the frame. You can see some of his cab mounting and crossmember work here.
Destined to tow a 24-foot trailer loaded up with steel on a regular basis, the HD’s stout AAM 1150 rear axle was predictably retained. And, with no need to reinvent the wheel, the factory leaf springs were left in their original stacks.

All HD Underneath

The frame, front and rear suspension, and receiver hitch from Phil’s ’06 Chevy donor were all salvageable and are currently in use. To accommodate the shorter body of the ’50, the frame had to be shortened, but neither the rear AAM 1150 and its leaf springs or the front AAM 9.25 IFS were affected. In fact, even the factory ’06 front skid plate is still employed. Retaining the bolt-in style OEM receiver hitch was mandatory, being that Phil uses the truck to haul steel for his business several times a month.

In the cab, the original dash layout remains intact, with a Vintage Air SureFit A/C system being added for a bit of modern day comfort. The slidebar radio (along with the rest of the stereo system) came from Custom Autosound. A Speedway Motors steering wheel is attached to a Flaming River steering column, and thanks to the Standalone Solutions’ wiring harness, even cruise control is functional.
A Mar-K Manufacturing custom bed has been treated to an aluminum floor with a wood grain laminate from Smokey Road Rod Shop. The floor offers the nostalgic look Phil was
after but is much more resistant to scratching, UV ray damage, warpage, and is water-resistant. The tailgate (also sourced from MAR-K) handle is positioned inside the bed
for a smooth, outward appearance.
Just as it did in the ’06 donor, four-wheel drive is engaged via the factory floorshift
NP261XHD transfer case. A slight lengthening of the engagement linkage was all
that was needed to make everything work like factory.
Upgrading the seating arrangement, Phil turned to Walton Fabrication for one of its Glide Engineering seat frames. The tapered, slit back seat frame offers a reclining mechanism, flips forward to access the spacious under-seat storage, and features gas shocks. The seat was upholstered by JCAT Customs in O’Fallon, Missouri. Eastwood’s X-Mat sound dampening insulation helps keep noise down in the cab.

While various mechanical upgrades have been made, the interior remains true to its roots, with the original dash and a bench seat. A SureFit air conditioning system from Vintage Air and a stereo from Custom Autosound complete with a slidebar radio add a few creature comforts, while a Flaming River steering column and Speedway Motors steering wheel replaced the original components. The bench seat consists of a Glide Engineering frame purchased through Walton Fabrication, which both reclines and flips forward, providing a significant amount of under-seat storage. The seat was upholstered locally by JCAT Customs. For sound deadening, X-Mat insulation from Eastwood got the call.


Being that the original rear bumper had disappeared long ago thanks to being an old farm truck, Phil decided to fab up his own. But instead of using a piece of channel or I-beam, he built a bumper from scratch that complements the truck’s body lines. The raw bumper was finished by St. Louis Powder Coat.
The original front bumper was re-chromed by Highline Plating in Cuba, Missouri. Then, to tie it in with the truck’s running boards and battery box, Phil added diamond plate to the top side.

Tow or Show

Making the project a family affair with his sons, along with enlisting the help of local shops whenever possible, definitely made the undertaking all the more special. But even though Phil has put together one of the nicest diesel repowers we’ve come across, he doesn’t plan to deviate from his original plan of using the truck to tow. Of course, the occasional trip to the local car or truck show is on the list as well. Rest assured, whether it’s earning trophies or earning its keep, Phil’s one-of-a-kind ’50 Chevrolet will get driven—and of course attract attention wherever it goes.

You May Also Like

Chevy Cummins Crew Cab

For the last 15 years, Chad Martin has been building award winning rides. This time, he built a Brutally Sexy Chevy for himself. From Chevy, […]

Inside Chevrolet Silverado And GMC Sierra HD’s

New Look, More Power, Enhanced Towing Technology Since 2011, General Motors’ HD line of trucks has been tough to beat. Powerful Duramax V-8’s in the […]