This 12-Valve Cummins-Swapped Custom Crew Cab 1970 K10 Packs 1,000 LB-FT And Shouldn’t Exist

Rather than some lost GM experiment, this custom 1970 Chevy K10 Crew Cab is a clean-sheet build by JPs Customs in Taylorsville, Utah. Known for high-end frame-off restorations, the shop created a truck that blends classic GM styling with modern engineering and serious Cummins turbodiesel power.

Owner John Pickering had a clear goal from the start: build a 1967–1972 GM four-door truck to a level no one else had reached. The finished product accomplished that goal and a turbodiesel engine was the powerplant of choice.

Modified TCI Pro 2 Chassis

Underneath, the truck rides on a Total Cost Involved (TCI Engineering) Pro 2 chassis, built around a triple-rail “Boxed Beam” frame. The design widens the frame ahead of the cab and narrows it toward the rear. This creates space for steering and exhaust while improving suspension geometry and overall stability. The platform also integrates upgraded brakes and a steering stabilizer. This gives the truck a solid, predictable feel that matches its performance.

To accommodate the Crew Cab configuration, JPs Customs stretched the chassis 33 inches at the center.

Torque-Oozing 12-Valve Cummins

The centerpiece of the build is a 5.9L 12-valve Cummins turbodiesel sourced from a 1998 Dodge 1-ton truck. Rebuilt and upgraded by Performance Diesel, the inline-six delivers 500 horsepower and a stout 1,000 pound-feet of torque.

Fuel is supplied through a custom 25-gallon tank. The filler is hidden behind the driver-side taillight, keeping the exterior clean while maintaining functionality.

Backing the Cummins is a 4L80E automatic transmission sourced from an early-2000s Chevy truck. It is controlled by a standalone computer from Compushift, tuned by Premier Performance, and paired with a 2,800-rpm stall converter. From there, power is routed through an Advance Adapters Atlas 2 transfer case with a 3:1 low-range ratio and twin-stick control.

Beefy Axles, Brakes, and Steering

To manage the torque output, the truck relies on Currie Enterprises axles. There’s a high-pinion 44 up front and a high-pinion 60 out back. Both housings are loaded with 4340 chromoly shafts, Eaton Detroit Truetrac limited-slip differentials, 1350-series pinion yokes, and 4.56 gears.

Braking performance comes from Wilwood, with 13-inch Superlite rotors at all four corners. Six-piston calipers handle the front, while four-piston calipers take care of the rear. The steering system includes Borgeson Universal box and RockJock high-steer forged knuckles.

Four-Link Suspension: Coilover Control

Suspension duties are handled by a custom four-link setup with coilovers at each corner. The system uses Fox 2.5 Performance Series remote-reservoir coilovers, each delivering 12 inches of travel, along with Fox 2.0 bump stops.

The link bars are built from 2-inch-diameter, 0.250-inch-wall tubing and use RockJock Johnny Joints to allow for articulation without sacrificing strength. The truck rolls on 37×12.50R18LT Toyo Open Country R/T tires mounted on 18×9 JTX Forged BD-212 wheels.

Factory Roots With Hand-Built Execution

The body is a combination of factory pieces and custom fabrication. It merges a 1970 three-door Suburban with a same-year Chevy pickup, both sourced from Idaho, while a fourth door was fabricated from scratch to complete the crew cab layout.

Additional exterior components include bed sheetmetal and a tailgate from Premier Street Rods, billet door handles from Ringbrothers, and door latches from Trique Manufacturing. The truck also uses Ford Mustang side mirrors, factory K10 trim, and custom rear-door trim. Wiring is handled by American Autowire and the truck is finished in Volvo Terra Brown.

Functional And Unique Interior

Inside, the truck carries the same level of detail as the exterior and chassis. One of the unique features is a flush-mounted safe from Liberty Safe, hidden behind the rear seat. It offers keyed and touchless entry along with internal LED lighting, providing secure storage without drawing attention.

The rest of the interior includes Dakota Digital gauges, seating from Slosh Tubz, upholstery by Darrell Burton Custom Auto Interiors, Relicate carpet, and a steering wheel from Sparc Industries. The rear seat began life as a factory K10 front seat before being reworked to match the rest of the cabin.

Built From The Ground Up In Only Three Months

The entire truck was completed in just three months by John Pickering, his 18-year-old son Lincoln, and 25-year-old Zachary Anderson. Considering the level of fabrication and engineering involved, that pace is as impressive as the finished product itself.

Photos: JPs Customs and Ken Brubaker