International Harvester 66 series

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.