Mil-Spec Automotive is quickly making a name for itself with modified Hummer H1 builds. The Michigan-based company's latest H1 was built for long trips both on and off road.

The 4-door hardtop H1 is powered by a General Motors-sourced 6.6-liter Duramax diesel V-8, making 500 horsepower and 1,000 pound-feet of torque. To give the truck more range for road trips and overlanding, Mil-Spec installed a 30-gallon aluminum fuel cell, protected by an integrated steel skid plate.

Power is sent to all four wheels through an Allison 6-speed automatic transmission. Mil-Spec installed its own driveshafts, carrier bearings, motor mounts, and transmission crossmember, as well as Wilwood 6-piston brakes. The Hummer rides on Toyo Open Country M/T tires, size 38x13.50R20.

The suspension is an upgraded "Baja" setup that boasts 13 inches of travel. Upgrades include longer coil springs, remote reservoir shocks, stronger front and rear ball joints, and a sway bar Mil-Spec said was designed for long travel.

2020 Mil-Spec Automotive Hummer H1

2020 Mil-Spec Automotive Hummer H1

Mil-Spec added a ceramic coating to the underbody and engine bay to improve heat insulation for the interior. The underside of the truck is also protected by skid plates, while a Bumper Tow Package adds a 2.0-inch ball hitch, electrical plugs, and a rearview camera for trailering. The exterior features a Deep Sky Black Kevlar-infused polyurethane  costing offset by semi-gloss black powder-coated trim.

In contrast to the H1's origins as a stripped down military vehicle, the interior of this truck features nappa leather upholstery with quilted stitching, custom lumbar supports for the seats, and a JL Audio sound system.

This particular H1 was built for a customer at a price of $300,000, but Mil-Spec can build a similar rig on request. In addition to Hummers, the company is branching out to the Ford F-150.