Compare/International Harvester 666 vs International Harvester 756

International Harvester 666 vs International Harvester 756

Verdict: International Harvester 666 vs International Harvester 756

The International Harvester 666 and the International Harvester 756 are both tractors — here is how they stack up on the figures that matter. International Harvester 756 leads on rated power with 76 hp against 75 hp. International Harvester 756 is the lighter machine (3,810 kg vs 6,780 kg), which helps on soft ground and transport, while the heavier model carries more ballast for traction-limited draft work. International Harvester 666 is the newer design (1972 vs 1967). In short: choose the International Harvester 756 for outright pulling power, or the International Harvester 666 if a tighter budget and lighter footprint matter more. Compare the full spec tables below before booking a demo.

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Acreage600 acBudgetMain crop / use

Fit & specs

International Harvester

Fit score

Best match

Clear

International Harvester

Fit score

Best match

Clear

Rated power

75 hp

76 hp

Confidence

40%

Guide price

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Overview

Manufacturer

International HarvesterReference

Diesel hydrostatic 2WDNovember 14 - December 3, 1973Link: Nebraska Tractor Test 1155 fileReference

With 18.4-30 rear tires.Reference

Total built

9,367Reference

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Original price

$11,875Reference

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Factories

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Rock Island, Illinois, USAReference

Engine

Gas Fuel tank

124.9 LReference

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Diesel Fuel tank

117.3 LReference

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Engine (gross)

55.9 kWReference

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Drawbar (claimed)

40.3 kWReference

51.5 kWReference

Drawbar (tested)

43.3 kWReference

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Displacement

4.8 LReference

Bore/Stroke

95 x 112 mmReference

Power (gross)

55.9 kWReference

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Fuel system

direct injectionReference

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Air cleaner

dual stage dryReference

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Compression

7.5:1Reference

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Rated RPM

2000Reference

2300Reference

Starter volts

12Reference

Coolant capacity

19.9 LReference

19.4 LReference

Power at rated engine speed

51.8 kWReference

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Max power

39.6 kWReference

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Fuel tank

—

124.9 LReference

Engine

—

75.3 kWReference

Power

—

75.3 kWReference

Oil capacity

—

8.5 LReference

Transmission

Torque-AmplifierReference

Torque AmplifierReference

Gears

10 forward and 2 reverseReference

16 forward and 8 reverseReference

Clutch

dry discReference

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PTO & Hydraulics

PTO (claimed)

51.5 kWReference

56.7 kWReference

PTO (tested)

51.9 kWReference

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Type

two-speed power shiftReference

Pump flow

45.4 lpmReference

Rear Type

IIReference

Rear PTO

independentReference

Rear PTO Type

540 (1.375)Reference

540/1000 (1.375)Reference

Power at rated PTO speed

48.8 kWReference

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Engine RPM

—

1000@2100Reference

Dimensions

Wheelbase

261 cmReference

256 cmReference

Weight

6780 to 7420 poundsReference

3810 kgReference

Front tire

7.50-16Reference

7.50-18Reference

Rear tire

15.5-38Reference

18.4-30Reference

Ag front

7.50-16Reference

7.50-18Reference

Ag rear

15.5-38Reference

18.4-30Reference

Length

408 cmReference

416 cmReference

Width

220 cmReference

203 cmReference

Height (steering wheel)

195 cmReference

208 cmReference

Shipping weight

3365 kgReference

3810 kgReference

Clearance (front axle)

53 cmReference

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Clearance (drawbar)

35 cmReference

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Bar rear axle

69 mmReference

82 by 2032 mmReference

Front tread

142 to 203 cmReference

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Rear tread

127 to 243 cmReference

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666 Serial Numbers

1972

7500Reference

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1973

8200Reference

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1974

11585Reference

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1975

13131Reference

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1976

15739Reference

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Location:

Clutch housing, right sideReference

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Electrical

Charging system

alternatorReference

Battery volts

12Reference

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Charging amps

—

55Reference

Diesel Batteries

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2Reference

Gas Batteries

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1Reference

Diesel Battery volts

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6Reference

Gas Battery volts

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12Reference

Diesel Battery AH

—

130Reference

Gas Battery AH

—

60Reference

Test results

Fuel use

20.1 l/hourReference

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Max pull

3769 kgReference

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Variants

Farmall 756

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row-crop tractorReference

756 Serial Number Location

756 Serial Numbers

1967 (Farmall)

—

7501Reference

1968 (Farmall)

—

9904Reference

1969 (Farmall)

—

14125Reference

1970 (Farmall)

—

17832Reference

1971 (Farmall)

—

18374Reference

1967 (IH)

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7501Reference

1968 (IH)

—

7672Reference

1969 (IH)

—

8164Reference

1970 (IH)

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8284Reference

1971 (IH)

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8427Reference

Speeds

Fit score weighs budget, operation size, crop match and data confidence against the details above. It’s guidance, not advice — always confirm with a dealer demo.