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Farmall 666 vs Farmall 766

Verdict: Farmall 666 vs Farmall 766

The Farmall 666 and the Farmall 766 are both tractors — here is how they stack up on the figures that matter. Farmall 766 leads on rated power with 80 hp against 75 hp. Farmall 766 is the lighter machine (4,672 kg vs 6,780 kg), which helps on soft ground and transport, while the heavier model carries more ballast for traction-limited draft work. Farmall 766 holds more fuel (140.0 L vs 124.9 L) for longer stints between fills. In short: choose the Farmall 766 for outright pulling power, or the Farmall 666 if a tighter budget and lighter footprint matter more. Compare the full spec tables below before booking a demo.

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Fit & specs
Farmall 666 Tractor
Farmall
62
Fit score
Best match
Clear
Farmall 766 Tractor
Farmall
62
Fit score
Best match
Clear
Rated power
75 hp
80 hp
Confidence
40%
40%
Guide price
Overview
Manufacturer
Farmall (a part of International Harvester)Reference
Farmall (a part of International Harvester)Reference
Diesel hydrostatic 2WDNovember 14 - December 3, 1973Link: Nebraska Tractor Test 1155 fileReference
Four gears (1-4) in two ranges (low/high) with the Torque Amplifer (TA) power shift. The TA allows a shift-on-the-move between direct drive and a lower speed.Reference
Total built
9,367Reference
10,799Reference
Original price
$11,875Reference
Engine
Gas Fuel tank
124.9 LReference
Diesel Fuel tank
117.3 LReference
Engine (gross)
55.9 kWReference
Drawbar (claimed)
40.3 kWReference
Drawbar (tested)
43.3 kWReference
54.7 kWReference
Displacement
4.8 LReference
5.9 LReference
Bore/Stroke
95 x 112 mmReference
98 x 129 mmReference
Power (gross)
55.9 kWReference
Fuel system
direct injectionReference
Air cleaner
dual stage dryReference
dual stage dryReference
Compression
7.5:1Reference
17:1Reference
Rated RPM
2000Reference
2400Reference
Starter volts
12Reference
12Reference
Coolant capacity
19.9 LReference
Power at rated engine speed
51.8 kWReference
63.7 kWReference
Max power
39.6 kWReference
54.7 kWReference
Fuel tank
140.0 LReference
Transmission
Transmission
Torque-AmplifierReference
Torque AmplifierReference
Gears
10 forward and 2 reverseReference
16 forward and 8 reverseReference
Clutch
dry discReference
dry discReference
PTO & Hydraulics
PTO (claimed)
51.5 kWReference
PTO (tested)
51.9 kWReference
63.7 kWReference
Type
two-speed power shiftReference
two-speed power shiftReference
Pump flow
45.4 lpmReference
45.4 lpmReference
Rear Type
IIReference
2Reference
Rear PTO
independentReference
independentReference
Rear PTO Type
540 (1.375)Reference
540/1000Reference
Power at rated PTO speed
48.8 kWReference
63.9 kWReference
Dimensions
Wheelbase
261 cmReference
266 cmReference
Weight
6780 to 7420 poundsReference
4672 kgReference
Front tire
7.50-16Reference
9.5L-15Reference
Rear tire
15.5-38Reference
18.4-34Reference
Ag front
7.50-16Reference
9.5L-15Reference
Ag rear
15.5-38Reference
18.4-34Reference
Length
408 cmReference
419 cmReference
Width
220 cmReference
248 cmReference
Height (steering wheel)
195 cmReference
Shipping weight
3365 kgReference
Clearance (front axle)
53 cmReference
Clearance (drawbar)
35 cmReference
35 cmReference
Front tread
142 to 203 cmReference
152 to 213 cmReference
Rear tread
127 to 243 cmReference
142 to 254 cmReference
Height (exhaust)
266 cmReference
Operating weight
4672 kgReference
Ballasted weight
5388 kgReference
666 Serial Numbers
1972
7500Reference
7416Reference
1973
8200Reference
9611Reference
1974
11585Reference
12378Reference
1975
13131Reference
14630Reference
1976
15739Reference
16840Reference
Location:
Clutch housing, right sideReference
Electrical
Charging system
alternatorReference
Battery volts
12Reference
Test results
Fuel use
20.1 l/hourReference
23.1 l/hourReference
Max pull
3769 kgReference
4189 kgReference
766 Serial Number Location
766 Serial Numbers
1971
7101Reference

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.

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