Allied Fab’s Ultra4 Chevy: Jason Weidhuner’s Ever-Evolving King of the Hammers Rig

AS SEEN IN OUR JULY/AUGUST 2026 ISSUE – Buy Now!

An Ever-Evolving Build

In the world of off-road racing, where trends change fast and fresh builds dominate social media, there’s something different about a car that’s lived a full life in the rocks. Not rebuilt for looks. Not retired after a few seasons. But evolved, repaired, and pushed year after year through some of the harshest terrain in the country. That’s exactly what Jason Weidhuner, owner of Allied Fab, has created: a purpose-built Ultra4 machine that wears its age like a badge of honor and still shows up ready to work.

Jason’s story with this car traces back to 2009, when he was helping friends campaigning S-N Fab race Hammers. That experience turned into something bigger the following year. In 2010, he stayed with the team and helped build the chassis from the ground up. That chassis, a 2010 S-N Fab Bravo, would become the foundation for a rig that’s still alive and evolving more than a decade later. By 2012 and 2013, the car was completed just in time to take on the brutal terrain of King of the Hammers. Despite the late finish, it proved itself immediately, landing an impressive 6th place out of 60 entries in the LCQ, a serious result for a freshly completed car.

Long before “patina builds” became a style, Jason’s car was already wearing its history on the outside. The body is a mashup of classic 1967–’72 Chevy C10 sheetmetal cut, stretched, narrowed, and repurposed to fit the chassis underneath. A ’68 front clip was narrowed 16 inches, ’68 doors were stretched 10 inches, rear fenders were built from ’72 front fenders, and a dash was formed from the front section of a ’72 hood. It’s not just unique; it’s intentional. Raw metal, aged finish, and real-world scars give the car a personality you can’t fake.

Underneath that vintage skin is a drivetrain and chassis setup designed for durability and repeat punishment. The chassis underneath all that patina beauty is a 2010 S-N Fab Bravo, and rocking in the front axle is a full Spidertrax 3.5-inch housing, Gearworks high-pinion 5.13 gears, a Detroit locker, and Chromoly knuckles and Cs. In the rear, there is an Eaton HO72, factory 5.13 gears, a Detroit locker, and a ¾-ton disc brake conversion. Powering the car is a tried-and-true LQ9 V8, upgraded with CNC-ported 5.3 heads, a Sloppy Stage 2 cam, and 40-lb injectors delivering reliable power without sacrificing longevity. Backing it all up is a rigid Turbo 400 transmission with a manual valve body and an Atlas 3.0 transfer case. It’s a combination built for consistency because finishing matters more than flash.

To keep the car planted and controlled across everything from high-speed desert sections to brutal rock climbs, Jason dialed in a suspension setup focused on strength and travel. In the front, he is rocking a single triangulated 4-link, 2.5 x 14-inch Fox IBP shocks, dual 2.0 bump stops, and aluminum links. The rear setup in this bad-to-the-bone rig is nothing less than a dual triangulated 4-link, 2.0 x 16-inch Bilstein coilovers, 2.5 x 16-inch Bilstein 4-tube bypass shocks, and aluminum links with a 1-inch sway bar. It’s a setup that reflects years of refinement, not theory. The car rides on a beautiful set of 17-inch Weld wheels, OMF beadlocks, and 40-inch BFGoodrich KR3 tires.

Inside, it’s all business, including AutoMeter gauges, PRP seats and harnesses, and Cerakoted aluminum floor pans. Everything serves a purpose. Nothing is there for show. This isn’t a one-season race car. Since its first competition runs, Jason has used the buggy to prerun King of the Hammers rock trails nearly every year. Like any machine that actually gets used, it has evolved from its 3rd front housing, 3rd rear housing, 2nd engine, and a 3rd transmission. That kind of turnover doesn’t mean weakness; it means the car is still in the fight. Jason describes the build in a way only someone who has lived with a car this long can. It’s like a gardener with a dead yard, something that’s been worked, rebuilt, and shaped over time. That’s what makes this Allied Fab Ultra4 car different.

It’s not about perfection. In an era where brand-new builds chase attention, Jason Weidhuner’s car stands as a reminder of what really matters in off-road racing. Seat time, durability, and a machine that refuses to quit. The best rigs aren’t the newest ones; they’re the ones that keep coming back. I want to thank Jason for allowing me to ride along with him out at Hammers in this badass rig and his entire crew for coming out and showing what the Allied name means! We will catch you on the next one, and like always, Tread on!