This Patent-Pending Ford F-Series Super Duty Six-Door Truck Kit Is A Big-Family Solution

In the diesel and off-road world, the most brilliant ideas rarely begin in boardrooms. They start with problems that persist. Long before six-door trucks became social-media curiosities or high-end custom builds, they were practical responses to something many families quietly struggle with: how to travel together without compromise.

That is the context behind the modern six-door truck and behind the rise of King Series, LLC. What started as a necessity for one large family has evolved into a refined, engineered approach to extended trucks—and, more recently, into a standardized system that could reshape how six-door pickups are built nationwide.

Announced December 9, 2025, from Emery, South Dakota, King Series has filed both design and utility U.S. patent applications for its standardized 6-Door Cab Kit. Designed specifically for modern Ford Super Duty platforms, this system brings OEM-grade engineering, repeatable precision, and long-term durability to a genre that has historically relied on improvisation.

When One Vehicle Isn’t Enough

In 2010, two families joined through marriage, instantly creating a household of eight. Every day logistics changed overnight. Camping trips, football games, church events, and holiday gatherings all required careful planning. With children too young to drive, every trip meant taking two vehicles. That solution worked mechanically, but not emotionally.

Road trips—traditionally times for shared conversation and collective memories—were split in half. Families arrived together but traveled apart. For parents who valued togetherness, that felt like a failure of design rather than circumstance.

Minivans (yuck) were the obvious answer on paper, but they came with limitations. Once fully loaded with passengers, cargo space disappeared. Towing capability was modest. Durability and long-distance confidence were not on the same level as a heavy-duty truck. The family needed something that could seat eight or nine people comfortably, haul gear, tow trailers, look cool, and still feel safe and capable on long trips. That was when the idea of a six-door pickup took shape. Rather than ostentatious excess, it was a necessity.

Why A Ford Super Duty Made Sense

The Ford Super Duty platform already checked many boxes. It offered strength, reliability, and the ability to tow campers, boats, and trailers without strain. Diesel power meant long-range efficiency and durability under load. What it lacked was interior volume for a huge family.

The challenge was obvious: factory four-door trucks weren’t designed for this use case. Extending the cab required addressing structure, safety, drivability, and comfort simultaneously. This wasn’t about adding seats wherever they fit. The goal was to create a vehicle that functioned as a cohesive whole.

Building The First Six-Door Truck

With a background in welding and mechanics, founder Chad Eddy approached the problem the way many diesel enthusiasts do—by building instead of buying. Using a Ford F-250 as the foundation, he spent months engineering and fabricating a six-door cab that could function like a factory vehicle.

The work went far beyond cutting and welding. Door placement, roof structure, interior layout, HVAC routing, and wiring all had to be rethought. The goal was not just to make it work, but to make it feel right. Once complete, the truck was finished in Ford Black and prepared for its first real test: a family road trip.

The Road Trip That Changed Everything

The results were immediate and undeniable. Every child had his own seat. Everyone rode together. Stops were simpler. Conversations flowed naturally. The truck transported the family and enhanced the overall travel experience.

The reaction from others was unexpected. At fuel stops and campgrounds, people asked questions. Families took photos. Kids waved. It became clear that this wasn’t a one-family problem with a one-family solution. Other families were seeing themselves in the truck. That realization marked a turning point.

From Family Experiment To Family Business

To gauge interest, the original six-door truck was put up for sale. The response was overwhelming. One moment stood out above the rest. A family from Platte, South Dakota—five kids with another on the way—came to see the truck. One of the boys climbed into the middle row, sat quietly for a moment, then hopped out, tugged on Chad’s sleeve, and said, “My butt feels pretty good in that seat.”

It was a small, honest comment, but it captured the essence of what families wanted: comfort, space, and dignity for every passenger. That first truck eventually went to a rodeo family in Kansas, where it continued its life filled with kids, gear, and miles on the road. What began as a family project had become a calling.

The Evolution Of Six-Door Trucks

Over the next decade, King Series refined its approach to six-door conversions, focusing almost exclusively on Ford Super Duty platforms. The emphasis was on OEM-style fit and finish, structural integrity, and long-distance drivability. While handsome looks always count, these trucks were expected to tow, travel, and work.

At the same time, the broader six-door market remained inconsistent. Many conversions were still one-off builds, heavily dependent on custom metalwork and improvised solutions. Quality varied widely, and long-term durability was often a question mark.

Why 2017 Changed Everything

When Ford introduced its all-aluminum Super Duty body in 2017, the rules changed. Methods that worked on steel-bodied trucks no longer applied. Door geometry, material behavior, and structural requirements became far more complex.

Some builders attempted to adapt by cutting factory doors, reshaping panels, and relying heavily on body filler to hide inconsistencies. While these trucks may appear acceptable initially, filler-heavy solutions often compromise alignment, durability, and long-term performance—especially under heavy towing or extensive use. King Series chose a different path: engineering instead of improvisation.

A Shift Toward Engineered Precision

Rather than modifying factory doors or stacking filler to make things line up, King Series developed new composite components designed specifically for six-door applications. This included a one-piece composite middle door engineered to factory hinge geometry and alignment, rather than one adapted from existing parts.

The approach prioritized structure first. During the conversion process, exterior panels and roof sections are removed, and the cab’s structural metal is fully welded from behind, ensuring strength where it matters most. Once the structure is complete, composite panels are installed to restore exterior uniformity with factory-tight tolerances. This process, refined over years of turnkey builds, laid the foundation for something bigger.

The Industry’s First Standardized Six-Door Cab Kit

When King Series announced that it had filed design and utility U.S. patent applications for a standardized six-door cab kit in December 2025, the goal was not to mass-produce trucks, but to bring consistency and repeatability to a market that lacked both.

The kit is designed for 2017–2026 Ford Super Duty platforms and includes composite outer side panels, a one-piece extended roof, and the patent-pending middle doors. Optional HVAC, wiring, and frame extension solutions enable builders to maintain full OEM functionality. For the first time, qualified body shops, upfitters, and advanced fabricators could follow a defined process rather than inventing their own.

Why Composite Construction Matters

Composite materials offer clear advantages on aluminum-bodied trucks. They reduce weight, eliminate corrosion concerns, and enable the production of complex shapes with repeatable precision. Just as importantly, they eliminate the need for excessive body filler.

The one-piece composite roof is a notable example. Traditional six-door builds often require welding multiple roof sections together, creating seams that must be filled and smoothed. A single-piece roof eliminates those seams entirely, improving both strength and appearance. For families who spend long hours on the road, these details translate into quieter cabins, better climate control, and long-term durability.

Diesel Power And Family Confidence

Although the cab kit supports both gas and diesel platforms, diesel Super Duty trucks remain central to the six-door concept. Torque, towing capacity, and longevity matter when a truck is carrying passengers, gear, and trailers long distances.

Equally important is how the truck drives. A six-door pickup must feel stable and predictable, not cumbersome. Proper frame extensions, suspension tuning, and weight distribution ensure that added length does not compromise drivability.

Why Six Doors Matter More Than Ever

Modern families differ significantly from those of decades past. Blended families, multigenerational travel, and active lifestyles place new demands on vehicles. The standard four-door truck, even at its largest, often falls short.

A well-executed six-door pickup offers seating for up to nine passengers, legit third-row comfort, diesel towing capability, and the safety and stability needed for long trips. More importantly, it allows families to travel together—without splitting into caravans of vehicles.

More Than A Truck

At its core, the six-door pickup is not about size for its own sake. It is about refusing to choose between capability and togetherness. It is about recognizing that the journey matters as much as the destination. What began as a necessity for one family has grown into a broader mission: helping other families stay together on the road, share experiences, and build memories in one vehicle. In an industry often driven by trends, the six-door truck stands out for an additional reason. It exists because it solves a real problem—and does so with engineering, purpose, and heart.