International Harvester 1566
Built: 1974–1976 · Series: 66 er-Serie
More machines from model year 1974
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International Harvester 66 series – the last Farmall tractors, 1971–1976: 666 to 1568, V8 diesels, Hydro 70/100, the articulated 4366
The 66 series was International Harvester's large-tractor programme of the early 1970s and the last range to carry the Farmall name – the register lists many models under both spellings. It replaced the 56 series in 1971 and brought the new cab, the Torque Amplifier powershift in improved form and the six-cylinder diesels D-360, D-414 and DT-436 from Melrose Park; in 1974 the upgrade followed with the 1568 and 1468, which carried a V8 diesel of 8,992 cm³ – the only production V8s in IH's tractor programme.
Read on 3 more paragraphs
The type number rises with output: 666 and 766 the mid-range, 966 and 1066 the 100 hp class, 1466 and 1566 the top models with turbo, 1468 and 1568 the V8 versions. Hydro 70 and Hydro 100 are the hydrostatic variants without a gearbox, ideal for loaders and specialty crops; the 4366 is an articulated four-wheel-drive tractor that IH had built by Steiger in Fargo from 1973. In the register the models run from 49.3 to 121.4 kW, 5,113 to 8,992 cm³ with six or eight cylinders, unladen weights from 3,719 to 9,838 kg, lengths from 4,089 to 6,121 mm and heights from 1,956 to 3,251 mm.
The 1066 with the DT-414 turbo diesel became IH's best-selling large tractor with over 50,000 units and is regarded in the USA as an icon of the red camp; the 66s were also the generation with which IH peaked shortly before the crisis of the 1980s.
Used 66s are common in North America and rare in Europe. When buying, the condition of engine and turbocharger, the Torque Amplifier (the clutch pack is the classic weak point), the hydraulics and, on Hydro models, the hydrostatic drive count.
Sources: SpecCodex register, model data: International Harvester 66er-Serie, International Harvester (Wikipedia)
Technical data
Engine
| Fuel | dieselcorrect |
|---|---|
| Power | 163 hp (120 kW)correct |
| Rated speed | 2,600 rpmcorrect |
| Cylinders | 6correct |
| Displacement | 7,139 cm³correct |
| Bore | 109.22 mmcorrect |
| Stroke | 127 mmcorrect |
| Compression ratio | 16correct |
| Cooling | water-cooledcorrect |
Dimensions and weights
| Length | 4,267 mmcorrect |
|---|---|
| Width | 2,845 mmcorrect |
| Height | 3,175 mmcorrect |
| Wheelbase | 2,662 mmcorrect |
| Ground clearance | 432 mmcorrect |
| Unladen weight | 6,892 kgcorrect |
Drivetrain and chassis
| Drive | rear- or four-wheel drivecorrect |
|---|---|
| Gearbox | 6 V/3 R and 12 V/6 Rcorrect |
| Front tyres | 10.00-16correct |
| Rear tyres | 2 x 20.8-38correct |
| Top speed | 30 km/hcorrect |
Origin and approval
| Construction | semi-frame constructioncorrect |
|---|---|
| Units built | 7,417correct |
Where this model stands
Power-to-weight ratio: 17.4 kW/t (120 kW / 6.9 t)
Power class: Large (100–180 hp)
Stronger than 86% of the tractors in the register — out of 15,663 models with a stated power figure.
Calculated from the documented figures above — not a rating.
Frequently asked questions
How much power does the International Harvester 1566 have?
The International Harvester 1566 delivers 163 hp.
How much does the International Harvester 1566 weigh?
The unladen weight is 6,892 kg.
What engine does the International Harvester 1566 have?
6 cylinders, 7,139 cm³ displacement, Diesel.
How fast does the International Harvester 1566 go?
Top speed is 30 km/h.
What are the dimensions of the International Harvester 1566?
4,267 mm × 2,845 mm × 3,175 mm.
When was the International Harvester 1566 built?
Production years: 1974–1976.
What to check before buying
- Check the hour meter against the service records — a replaced instrument is the most common gap.
- Compare the data plate and chassis number with the papers.
- Check the weights in the papers against the figures here — attachments change them.
- Check front and rear tyre sizes: mismatched pairs strain the drivetrain.
- Shift the gearbox cold and warm — jumps only show up at temperature.
- Load the hydraulics and watch for sag.
- Ask about parts availability for this build year — the running costs hang on it.
A general list for this type of machine — no substitute for an inspection or an appraiser.
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This page carries 23 individual figures for this model. They come from 2 recorded sources; every figure can be traced there. What we cannot document is not here — we leave gaps open rather than estimate them.
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Other models in this series
Sources: Wikibooks Traktorenlexikon (CC BY-SA 4.0) (retrieved August 2026) · Wikipedia (retrieved August 2026) · How we check the data
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