Ah, the Wagoneer. Sold under the names Willys, Kaiser, American Motors, and Chrysler.
Fun factoids: First, it had a longer production run than the VW Beetle had in the US (although worldwide manufacture of the Beetle was considerably longer, in third-world countries). The Wagoneer/J-Series/SJ-Series had fewer changes than even the Beetle - only trim and grille stampings, engine and transmission and driveline choices. The wheelbase was contracted an inch in the 1970s, for reasons unknown - the chassis was not altered.
For all its significance, it was not a breakthrough - it was a milepost. It was the logical evolution of the Jeep Basket-Weave station wagon; incorporating ideas used in the International Travelall and Chevrolet Suburban. With the A-Series of light trucks, IH introduced the idea of rear doors to the segment of passenger-adaptations of panel trucks. The Suburban was still two-door, with sliding windows where the panel truck would have metal walls.
It was amazingly successful - the right car at the right time. The J-Series was conceived to help Willys re-enter the passenger-car market...it was owned by Kaiser Industries from 1955. Henry Kaiser's obsession was to create his own car company, and he'd already failed on his first attempt, Kaiser-Frazer. He bought Willys for pennies on the dollar - it was headed for bankruptcy - and turned to what he knew, government contracts. Willys abandoned their postwar car line, but Henry intended that to be temporary.
First, he had to get market legitimacy. That meant models that drew on Willys credibility with their military jeeps, and that was what the J-Series was to do. An obvious suburban-homeowner car, yet equally-obviously tied to the Jeep legacy. Then, an overhead-cam six - that was a first for a domestic maker, and as it turned out, a bridge too far. There was much Henry Kaiser didn't understand about auto manufacture. The six was a good engine, but needed development work that Willys couldn't afford. It got it later as the design was sent to Kaiser Argentina, and made for 20 more years.
It was launched, and it sold as well as planned, but acceptance was slow. There wasn't that much faith that the new car company named Kaiser would last any longer than the previous one. Railroads and parks departments bought them, and a few private users who didn't care what the neighbors thought. I know that last; my father had one.
Just as sales were catching on, Henry Kaiser died (1967). He owned his businesses outright, and estate planning, if there was any, was minimal. All the components of Kaiser Industries had to be sold.
The current assertion was, Kaiser Jeep was sold to American Motors because it was in trouble. It was not; it was having one of its best years, in 1969. The problem was, its production capacity at Toledo was being exceeded. It was not going to expand, not when the Kaiser family was about to sell it for taxes. Products in 1968-69 were rushed out the door and quality suffered.
American Motors bought them, with borrowed money. And it took AMC about ten years to figure out what to do with it - with disastrous cost-cutting (thinner steel, engineering shortcuts) the first eight years. They did figure things out - their XJ Cherokee line was as brilliant as the J-Series - but it was too late; by then, AMC was out of money and owned by Renault. Soon to be sold, as Willys-Overland and then Kaiser-Jeep were.
But, in terms of development...the Wagoneer fits right in with the progress, from the Willys MB military, to the Basket-Weave wagon, to the J-Series, and then the AMC Eagle, designed by engineers on the Jeep side. It was the civilizing, and the melding, of the 4wd auto/truck/SUV.
There is a lot of automotive history behind that. And a lot of stories that now seem lost. For example, it appears that Henry Kaiser and his son, Edgar, had planned a takeover of American Motors before his death and the chaos of estate taxes. One way they got AMC to buy Jeep was, Kaiser Industries owned a large bloc of stock. They proposed it to AMC, which was not in financial shape to really do it, and forced a vote against the wishes of a majority of AMC top management.
Had Henry lived, or planned his estate better, it could have been an announcement of AMC being purchased by Kaiser Industries. How that might have worked out in later years for AMC would be interesting.