As the 1960s dawned, International Harvester was sitting high atop the pyramid of American heavy truck builders.

One of the oldest and best-known American companies in existence, Harvester's roots went back to the 1840s, when Cyrus McCormick, inventor of the horse-drawn reaper — one of the first mechanical harvesting machines — revolutionized American farming.

In 1902, McCormick’s company joined forces with two other farm machinery manufacturers to form the International Harvester company. The new conglomerate, one of the first large corporations in the U.S., began moving away from steam-powered tractors and farming machinery toward the then-new internal combustion engine and emerging automotive technology.

Farm tractors were naturally the company’s initial focus for automotive machines. But it quickly became obvious that once the crops were in, farmers needed some sort of heavy-duty automobile to help them carry them to market.

As a result, the very first International truck, the Auto Wagon, appeared in 1907. The right-hand steer Auto Wagon was simple and tough, with high ground clearance that performed well on the poor – or even nonexistent – roads of the time.

Eventually, International Harvester would become a massive global company. Its name would grace light-duty pickups, SUVs, lawn and garden equipment, construction machinery and even home appliances and electronic goods.

But heavy trucks increasingly became a core competency for International. In fact, Navistar Trucks is today the last surviving business division of the once-massive International Harvester Corporation.

Transtar Rising

As the company headed into the 1960s, its heavy truck division was at the top of its game. Its “Emeryville” series of 1940s and 1950s cabover models had earned a reputation for reliability and toughness. And the trucks’ striking “bullnose” front ends remain an enduring style point for trucks of the era and collectors’ favorites today.

But the long-haul Class 8 cabover market was changing. As new sections of the Interstate highway were completed, truckers were able to take on longer routes. And the need for spacious, comfortable interiors, combined with powertrains and chassis able to tackle these tough, new long-haul applications, was apparent.

In the early ‘60s, the International DCOF-405 Emeryville cabover had been the top-selling American heavy truck for four years running. In 1965, International capitalized on that design with the introduction of the CO-4000 cabover tractor.

The new tractor featured a larger and wider cab. It was taller than its predecessor, with more rounded edges. A large, trapezoidal grille with angular accent lines emphasizing its outline dominated the front end of the truck – an iconic styling point that would remain a feature of International cabovers well into the 1990s.

The Transtar name was first affixed to the CO-4000 in 1968. That year, the standard engine was the IHC DVT573 turbocharged diesel. Cummins and Detroit Diesel engines were offered as optional specs.

The ride could be a little rough, as the trucks came with rubber block suspensions (air ride was not available yet). And, like with all cabovers, the cab tended to be chilly in the winter. Engine noise could be intense, especially at higher rpm.

On the other hand, the truck got high marks for its looks, turning radius and interior amenities.

New Transtar Models and Features

The Transtar was a hit. In 1970, International decided to capitalize on its popularity with two new models, including a “Super Transtar” and a short-lived “Unistar” all-wheel-drive variant. The Super Transtar featured a 12V72, V-12 Detroit Diesel engine capable of pulling loads up to 144,000 lbs.

Another major upgrade came in 1974, when the Transtar II was launched. Most of the enhancements were under the hood. Visually the trucks looked nearly identical. New, more powerful diesel engines were becoming popular, and the Transtar II took advantage of this trend with a larger, redesigned engine compartment.

You could spec the truck with a standard IHC V800 turbocharged V-8. The Detroit Diesel engine offering was upgraded from the 12V71 to the 8V92 V-8. You could also spec a Caterpillar 3406, six-cylinder diesel, as well as several Cummins options, including the massive KT-450 with a whopping 1,150 cubic-inch displacement. It remains one of the largest diesel engines ever fitted to a serial production commercial vehicle.

Beginning of the End for COE Trucks

Changes to tractor-trailer length laws in 1976 heralded the beginning of the end of the Class 8 cabover in North America. Class 8 conventionals, which offered drivers much more room and a smoother ride, saw an immediate spike in sales.

The International Transtar II ceased production in 1981, replaced by International’s new Newport Series cabovers, which featured a completely flat cab floor in order to maximize interior space and compete with conventional model trucks.

All International cabover production finally ceased in 1991.

One Driver's Memories of the International Transtar

“I loved that truck,” says HDT contributing editor Jim Park. He drove one in the late 1970s during his tenure as a professional driver. “It had a smooth ride – although that was dependent on the wheelbase. The longer-wheelbase Transtar was really smooth. But any short wheelbase cabover will beat the snot out of you. But it was a really nimble truck. And it had a lot of power for its time, too.”

The smaller cab wasn’t a problem, either, Park says. “I liked a smaller cab,” he says. “The Transtar doghouse was low. So it was really easy to get in, and out of the seat and into the bunk. Some of the other trucks at the time had really high doghouses – which were a pain to deal with. They were just really good trucks for that time.”

Hear from an International Transtar Truck Collector

“They’re rough riding,” says Transtar collector Mike Britton. He’s owned a 1976 model that he bought in 2015 and did an extensive restoration on.

“You don’t feel a bump in the road once in a Transtar,” he quips. “You feel it three times! And they’re a little bit louder than a conventional truck. But not too bad.”

Britton exhibits his Transtars at antique truck shows in and around his native Missouri. And he says the reactions he gets at the shows are remarkable.

“Every show,” he says. “It’s unreal how many guys come up to me and say, ‘My dad had one of these!’ or ‘I started out in a Transtar just like this one!’ That’s why when I decided to name the truck, I called it ‘Remember When,’ because of all the good memories it brings to people.”

The International Transtar and Transtar II were excellent trucks that made the most of the regulations and technology of the time. Fleets and drivers alike loved them. And, over time, they became mainstays on North American highways. Today, they are instantly recognizable to trucking enthusiasts who remember those days, and nearly extinct cabover trucks, fondly.