When engineers at Kaiser first put pen to paper in the early 1960s designing a new SUV, it's almost certain that none of them expected the rugged people mover would be built nearly without change for an astounding three decades. The Full-Size Jeep, or FSJ/SJ platform, as it came to be known, was introduced to keep Kaiser ahead of Detroit's bigger automakers in the race to fill the budding four-wheel-drive vehicle market. Back then, the term "SUV" hadn't been invented, and the mainstreaming of vehicles such as the Full Size Jeep was decades away—and yet, the big Jeep would live long enough to see both.

In contrast with its ultimate lasting power, the Jeep's success was at first far from a sure thing. Even though the Willys-Overland division had had some luck with the Jeep Station Wagon, the new Full Size model would need to appeal to a wider range of potential buyers in order to justify its $20 million development. A design brief unlike any other in the existing rough-and-tumble truck world was put forth. Dubbed the Wagoneer, the vehicle would need to deliver carlike handling while still retaining the ability to go nearly anywhere without getting hung up or stuck. This mean balancing respectable ground clearance with the dignities of passengers entering the SJ in formal dress. It also needed to move away from the "it's also a wagon" afterthought styling of the older Willys and instead present a compelling package that would bring new business to the brand.

Willys-Overland turned to Brooks Stevens, the decorated industrial designer who was also working with Studebaker on a similarly-named, yet significantly smaller wagon, the Wagonaire. Like the Stude, the Jeep would count a magnificent greenhouse and strong, square-jawed mug among its standout attributes. Unlike its contemporaries from General Motors (the Suburban), its low bodywork gave it a more approachable character suited for everyday use, with all of the off-road gear tucked neatly up under the platform as high as it could go. From this simple format, the un-trucky Jeep wagon would spawn multiple variants and, much later on, would almost single-handedly create the concept of a high-end, pricey luxury SUV in the American market.

See All 31 Photos

1963-1969: Basic Bits, Not-So-Basic Beginnings

To give the Wagoneer the greatest possible chance to find an audience, Jeep began churning out not just the four-door, family-friendly model but a panoply of "let's see what sticks" editions, including a sporty two-door, a panel delivery, and the Gladiator pickup, all for the 1963 model year.

Each of these variants was available with the option of four-wheel drive as well as an unusual independent front suspension setup, regardless of how many wheels were driven. Consisting of a set of swing axles and centered by a Dana differential, it was a trouble-prone design that didn't survive past the first couple years of production; it would be replaced by a more common solid front axle setup, which would ride under all Full-Size Jeep models from then on. Four-wheel drive would become standard by 1967.

The Kaiser Jeep Wagoneer's original engine was a 3.8-liter straight-six good for a modest 140 horsepower. Ubiquitous throughout the Jeep lineup, the six would be briefly joined by a second, less-powerful 133-hp variant the following year, before being replaced by a pair of American Motors power plants in 1965. These included a 3.8-liter of AMC's design, as well as a 5.4-liter V-8 that delivered 250 to 270 horsepower depending on trim level. Eventually, Jeep would even turn to Buick for a 230-hp, 5.7-liter V-8 in 1968.

See All 31 Photos

1970-1979: Ever More Family-Friendly

Perhaps more important than the Wagoneer's towing and trail-friendly mechanicals were its creature comforts. By the time the Super Wagoneer appeared on the scene towards the end of its first decade (pictured above), the SUV was offering power assists and accessories more commonly found in near-luxury passenger cars. GM, Ford, and Chrysler were only just starting to wake up to the profit potential of trucks aspiring beyond their agricultural station, which gave Jeep a significant head start in attracting buyers unwilling to tolerate a rock-hard ride in a rattling tin can. Fellow SUV pioneer International-Harvester never made this pivot, by the way.

When Kenosha-based AMC fully acquired the Jeep brand in 1970, it was able to turn its production acumen towards further refinement of the Wagoneer's wares. Recognizing the timeless nature of the SUV's design, or perhaps simply operating on a shoestring budget, the automaker would swap taillights and grilles every few years but leave the vehicle's sheetmetal largely untouched.

By 1972, however, AMC started installing one of two motors that would come to define the full-size Jeep for the remainder of its lifecycle: A 5.9-liter V-8 good for between 140 and 200 horsepower and 280 lb-ft of torque (depending on the emissions regulations of the day), and a 4.2-liter straight-six that pumped out 110 horses and 210 lb-ft of twist. A slightly-larger 6.6-liter mill was also available on and off throughout most of the '70s, alongside a smaller 200-hp 5.0-liter V-8 in the pickup, which dropped the Gladiator nomenclature in favor of the J-Series badge.

AMC also reinstated the two-door edition of the SJ platform by way of the Cherokee model, which eventually graduated from Quadra-Trac four-wheel drive to a more advanced Selec-Trac setup, and which could be had in both narrow and wide-body (flared-fender) looks. Confusingly, a four-door Cherokee was also eventually brought to market alongside the four-door-only Wagoneer, before the former model was discontinued entirely in 1983.

See All 31 Photos

1980-1991: Significant Impact

AMC was in a shambles in the early 1980s. The company had formed a desperate alliance with Renault, and was counting on a new Jeep—the smaller, unibody XJ Cherokee—to save its bacon. Still, it kept the FSJ in the mix, continuing to sell J-Series trucks and pushing the four-door further and further upmarket until only a loaded model, christened the Grand Wagoneer for 1984, was available.

The Grand Wagoneer would be the SJ platform's swan song, outlasting the pickups (which were canceled in 1988) and bolstering the woodgrain-sided Jeep's legend. A generation would grow up with the Grand Wag seared into its consciousness thanks to rides in the comfy cruiser's rear seat or by spotting one dropping classmates at school or barreling down highways on family road trips. Essentially mono-spec with only a few options, the Grand Wagoneer's popularity among the East Coast jet set would be enough to keep production lines humming past Chrysler's purchase of Jeep in 1987, all the way until creeping safety and efficiency regulations would cancel it for good after 1991.

The full-size Jeep platform's legacy is extensive. In addition to proving that the general public would pay a premium for modern luxuries in non-cars, even those with an older design, the big SUVs and trucks helped keep Jeep (and its various suitors) afloat during some pretty lean years. The earlier models proved that buyers were increasingly enamored by adventurous vehicles—so long as those vehicles could be comfortably driven to and from work most of the time. Near the end, the Grand Wagoneer proved the linchpin of the premium SUV movement that would accelerate throughout the 1990s, culminating with ever-more-luxurious Range Rovers and the original Cadillac Escalade. So, the next time you stare at some hulking modern SUV, possibly even Jeep's impending Grand Wagoneer redux, and wonder "how did we get here," you can thank the FSJ.

Read MoreHistory of the 1984-1991 Jeep Grand Wagoneer

The Suzuki Jimny Makes a Great Vintage Ford Bronco Clone

Obscure SUVs You Definitely Didn't Know Existed

See All 31 Photos