The John Deere 301A is a 2WD industrial tractor manufactured by John Deere in Dubuque, Iowa, USA from 1973 to 1981.
The John Deere 301A is equipped with one of two engines: a 2.5 L (152.0 cu·in) three-cylinder diesel engine or a 2.7 L (164.0 cu·in) three-cylinder gasoline engine and one of two transmissions: a collar shift transmission with 8 forward and 4 reverse gears and mechanical dry disc clutch or a power shuttle transmission with 8 forward and 8 reverse gears and hydraulic wet disc clutch.
The tractor could be equipped with the following engines:
- John Deere. It is a 2.5 L, 2,490 cm2, (152.0 cu·in) three-cylinder natural aspirated diesel engine with 98.0 mm (3.86 in) of the cylinder bore and 110.0 mm (4.33 in) of the piston stroke. This engine produced 46.6 PS (34.3 kW; 46 HP) at 2,500 rpm of output power.
 - John Deere. It is a 2.7 L, 2,688 cm2, (164.0 cu·in) three-cylinder natural aspirated gasoline engine. The cylinder bore is 102.0 mm (4.02 in) and the piston stroke is 110.0 mm (4.33 in). This engine produced 46.6 PS (34.3 kW; 46 HP) at 2,500 rpm of output power.
 
The JD 301A is equipped with power steering, hydraulic wet disc brakes, open operator station or two-post ROPS and canopy (optional) and 73,8 liters (19.3 US gal.; 16.1 Imp. gal) fuel tank.
John Deere 301A Specifications
| General Specifications | |
| Model | John Deere 301A | 
| Length | 3,070 mm (120.9 in) | 
| Width | 1,900 mm (74.8 in) | 
| Height | 2,180 mm (85.8 in) | 
| Wheel base | 1,880 mm (74 in) | 
| Weight | 2,080 kg (4,586 lbs) | 
| Fuel tank capacity | 73,8 liters (19.3 US gal.; 16.1 Imp. gal) | 
| Battery | One or two 12V | 
| Cabin type | Open operator station or two-post ROPS and canopy (optional) | 
| Engine | |
| Engine model | John Deere | 
| Engine type | Four-stroke, liquid-cooled, inline | 
| Cylinders | 3 | 
| Fuel type | Diesel | 
| Displacement | 2.5 L, 2,490 cm2, (152.0 cu·in) | 
| Bore and stroke | 98.0 mm X 110.0 mm (3.86 in X 4.33 in) | 
| Horsepower | 46.6 PS (34.3 kW; 46 HP) at 2,500 rpm | 
| Torque | 149.2 N·m (15.2 kg·m, 110 ft·lb) at 1,300 rpm | 
| Starter | Electric | 
| Oil capacity: | 5.7 L (6 US. qt, 5 Imp. qt.) | 
| Coolant capacity: | 11.4 L (12 US. qt, 10 Imp. qt.) | 
| Engine | |
| Engine model | John Deere | 
| Engine type | Four-stroke, liquid-cooled, inline | 
| Cylinders | 3 | 
| Fuel type | Gasoline | 
| Displacement | 2.7 L, 2,688 cm2, (164.0 cu·in) | 
| Bore and stroke | 102.0 mm X 110.0 mm (4.02 in X 4.33 in) | 
| Horsepower | 46.6 PS (34.3 kW; 46 HP) at 2,500 rpm | 
| Torque | 149.2 N·m (15.2 kg·m, 110 ft·lb) at 1,400 rpm | 
| Starter | Electric | 
| Oil capacity: | 5.7 L (6 US. qt, 5 Imp. qt.) | 
| Coolant capacity: | 11.4 L (12 US. qt, 10 Imp. qt.) | 
| Transmission and chassis | |
| Chassis | 4×2 2WD | 
| Steering type | Power | 
| Brakes | Hydraulic wet disc | 
| Final drive | Inboard planetary | 
| Differential lock | Mechanical rear | 
| Transmission model | – | 
| Transmission type | Collar shift with mechanical dry disc clutch | 
| Gears | 8 forward and 4 reverse | 
| Transmission model | – | 
| Transmission type | Power shuttle with hydraulic wet disc clutch | 
| Gears | 8 forward and 8 reverse | 
| Speed | Forward: 25.3 kmh (15.7 mph) Reverse: 29.4 (18.3 mph) | 
| Tires | |
| Front tires |  Lawn/turf: 27-9.50-15 Industrial: 6.50-16, 11L-15, 7.50-16, 8.00-16  | 
| Rear tires |  Lawn/turf: 18.4-16A Industrial: 13.6-28, 14.9-24, 16.9-24, 17.5L-24  | 
| Three-Point Hitch | |
| Caterogy | II/I | 
| Control type | – | 
| Lift capacity (at ends) | – | 
| PTO (Power take-off shaft) | |
| Middle PTO type | Live | 
| Middle PTO speed | 1,000 rpm | 
| Rear PTO type | Independent | 
| Rear PTO speed | 540 rpm | 
| Hydraulic system | |
| Hydraulic type | Closed center | 
| Hydraulic capacity | 37.9 L (40.05 US. qt, 33.35 Imp. qt.) | 
| Pressure | 2350 psi (162 bar) | 
| Total flow | 13.0 gpm (49.2 lpm) | 

I have a JD 301 – 1973 I’m looking to install Hydraulic top link. The mechanical top link is 20″ How much stroke should I install 8″ 12″