The 2+2 Tractor: International Harvester

Almost from the beginning of the farm tractor, farmers and engineers fooled around with coupling two tractors together to put more power to the ground. In 1970, International Harvester played the same game a little more elaborately. They took the final drives from two 1066 tractors, used the transfer case from a 4166, made the tractor pivot in the center and mounted the engine out in front of the front wheels. The control station was still back by the rear wheels and the result was a tractor with a lot of possibilities.

Development continued through the 1970s until the “final answer” debuted in January 1979. They called them the 2+2 and they were unique in the market. The name-calling started right away. Some of the more polite ones included “anteater,” “land shark,” “worm” and “Snoopy,” but the names were used with a smile on the face once the tractor was seen in operation. The 2+2 has been described a lot of ways but in essence it was a rowcrop tractor with some of the features of a big, articulated four-wheel-drive tractor. It had unparalleled maneuverability (for a four-wheel-drive rowcrop, that is) and put a lot of power to the ground. Up front, the overhanging engine gave front wheels a lot of grip and once the rear was hooked up to an implement, the draft forces loaded the rear tires.

Two models were offered initially, the 3388 and the 3588. The design had changed considerably over the years in development. The rear final drive was from a 1086 tractor and the cab came from that as well. The front axle was a Kimco unit from Japan and a transfer case connected the front and rear sections. The engine drove the transmission and transfer case in the rear section through a driveshaft. The weight balance was very different from a traditional rowcrop, with a 54/46 distribution versus a 30/70. With draft, the weight shifted to more of a rear bias. The 2+2 used the same size tire front and rear, a standard 16.9-38 or an optional 18.4-34.

The 3388 mounted a 130 PTO hp DT436B turbo diesel while the 3588 had the now legendary DT466B. In 1980, the 3788 joined the herd and it was rated at 170 PTO hp with an uprated DT466. The powertrain was also uprated, with the rear final drive coming from a 1586 tractor. The cab also came from the 1586 and was a bit of an upgrade over the smaller units.


The DT466 was one of IH’s home runs. It grew out of the 400 series that debuted in 1971 after a $25 million dollar development program. The first two in the series were the D414 and D436. The D466 debuted later and before long they were turbocharged (and got the “DT” in the designation). The DT436 and DT466 lived to power the 2+2 tractors right to the end, but when IH was sold, the engine stayed with the Navistar engine group. In this era, the DT466 was tuned to several power levels and would later increase even more. By the time the 2+2 tractors debuted, the B-series engines were available with better crankcase ventilation; piston, ring and liner upgrades; and improved cam, lifters and rocker arms.
Hoshock demonstrates how the hood is opened to gain access to the DT466 engine.
The anteater nickname is not hard to figure out but the long nose was deliberate. That overhang put 54 percent of the weight over the front wheels. The 2+2 was not intended for much ballast. They were so well balanced they didn’t need any… according to IH anyway. That didn’t stop people from adding weight, sometimes contributing to an early demise. The 1980 Nebraska tractor test unit used rear tires ballasted with an extra 2,000 lbs of chloride. There were no provisions for iron ballast.
The 2+2 isn’t all that long in the wheelbase department… not much different than a big rowcrop tractor. It’s just that engine hanging out over the front that makes it look huge. In reality it’s just an extra-burly, extra-capable rowcrop tractor and that’s how it was intended to be used. The 2+2 had a convertible Cat II/Cat III hitch system and draft control, as well as an optional 1,000-rpm PTO, fixed drawbar, sequential-raise hitch, a sway limiting device and as many hydraulic couplers as you needed.

The 2+2 tractor required some getting used to and a farmer used to a regular rowcrop had a learning curve. Some developed an almost instant hate relationship with the tractor, but those who stuck with it learned how to make it work. IH knew it would be an uphill battle promoting the tractor and, of course, the competition was not kind. Yet when IH did side-by-side comparison tests, the 2+2 very publically blew the competition away.

There were teething problems, of course. Nothing super-major or embarrassing, but the hydraulics were probably the weakest link. Muffler and air cleaner troubles existed too. Those problems would be quickly solved. Long term, the farmers who didn’t maintain these very complex units faced some expensive fixes. The pivot points on the tractor and the driveshaft U-joints were two of these areas.

“Today, many of the 10,000 2+2 tractors built are still in operation. More than most tractors, the feelings about them run to the extremes.”

Ultimately, even the 1086 final drive proved too weak for the gutsy DT466, which owners insisted upon turning up. IH knew the potential of this tractor was limited by this final drive and they continued to work towards an upgrade all the way to the end.

For 1982, the line of tractors was upgraded from the 30 series to the 60 series. The 3388 became he 6388, the 3588 the 6588 and the 3788 the 6788. Changes were minor, but the models were becoming more refined as time went along and were gaining more acceptance in the market.

The cab was very similar to the 1586 tractor, but with the necessary control changes. An interior upgrade was offered for the 2+2 and called the Western. It included embossed vinyl trim panels with nicer trim, a high stereo with a cassette and a digital clock. John says the 2+2 is quite a comfortable place to work. Early 2+2s were plagued with a muffler defect that caused a loud and extremely annoying whistle when the engine was working hard.
The view over the hood in a turn was more than a little disconcerting for farmers used to conventional rowcrop tractors. It’s worth remembering that this tractor was marketed in the realm of the large rowcrop tractors and that’s who was buying the 2+2s. Even the really big farmer who needed a high-horsepower articulated four-wheel-drive tractor would have been a bit disconcerted because those tractors usually had a center-mounted cab. The rear cab was a boon to a rowcrop farmer who needs to be able look back and see his three-point hitch. With a heavy draft load, the 2+2 steered more like a conventional tractor because the load kept the rear section more in line.

The 2+2 tractors came to an end shortly after Case and the agricultural component of IH merged to form Case International (later just Case IH). Case was the stronger partner and the new Case International engineering department was more Case than International. As a result, the 2+2 was dropped, probably with a disdainful sneer. Many think they were hasty. IH was on the verge of having a new final drive available that could have opened the door to an even more powerful and versatile 2+2. The new trans was good enough that it became the foundation for several very successful Case IH tractors.

Today, many of the 10,000 2+2 tractors built are still in operation. More than most tractors, the feelings about them run to the extremes. It’s either vile loathing or devoted love… nothing inbetween! John Hoshock, the owner of this 1980 3788 falls into the latter category. He bought the unit in 2004 as the big tractor for his medium-sized Ohio farming operation and hasn’t regretted the purchase. He gets a little good-natured flack from his farming buddies but, again, the “anteater” just blows them away out in the field. DW

[divider]Typical Specifications: 1981 IH 3788 2+2[/divider]

Engine: Six-cylinder Turbo Diesel, IH DT466B
Displacement: 466 cid
Bore & Stroke: 4.30 x 5.35 inches
*Rated Drawbar Power: 142 hp @ 2,499 rpm
*Rated PTO Power: 170.57 hp @ 2,500
Compression Ratio: 163:1
Transmission: 12-speed w/optional torque amplifier
Weight: 18,620 lbs
Wheelbase: 110 inches
L x H: 228 x 116
Fuel Capacity: 90 gal (main), 63 gal (aux.)
Tires: 18.4-38
*Fuel Consumption: 10.9 gph @ full power
*Drawbar Pull: 19,069 @ max power
*Top Speed: 19.6 mph

* As Rated by Nebraska Tractor Test 1377

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