
Allis ChalmersModel A
Allis Chalmers D21 Series II
Row Crop
- power
- 121 hp
- displacement
- 426 ci
- Cylinders
- 6
- Forward gears
- 8
Head to head · Row Crop

Row Crop
Utility
How they compare
D21 Series II is in the 40th percentile; 6620 Premium (2003-2006) is in the 42nd · 1,206 models
D21 Series II is in the 72nd percentile; 6620 Premium (2003-2006) is in the 66th · 1,409 models
D21 Series II is in the 50th percentile; 6620 Premium (2003-2006) is in the 50th · 1,417 models
D21 Series II is in the 28th percentile; 6620 Premium (2003-2006) is in the 46th · 1,350 models
Full comparison
| Spec | Allis Chalmers D21 Series II | John Deere 6620 Premium (2003-2006) | Difference |
|---|---|---|---|
| Manufacturer | Allis Chalmers | John Deere | — |
| Model | D21 Series II | 6620 Premium (2003-2006) | — |
| Category | Row Crop | Utility | — |
| Spec | Allis Chalmers D21 Series II | John Deere 6620 Premium (2003-2006) | Difference |
|---|---|---|---|
| Manufacturer | Allis Chalmers | John Deere | — |
| Model | 3500 | 6068T 4V-CR | — |
| Power Output | 121hp | 125hp | ▲ 6620 Premium (2003-2006)+4 hp · +3% |
| Rated RPM | 2,200RPM | 2,300RPM | ▲ 6620 Premium (2003-2006)+100 RPM · +5% |
| Cylinders | 6 | 6 | Same |
| Displacement | 426ci | 414ci | ▲ D21 Series II+12 ci · +3% |
| Bore | 4.3in | 4.2in | ▲ D21 Series II+0.1 in · +2% |
| Stroke | 5in | 5in | Same |
| Spec | Allis Chalmers D21 Series II | John Deere 6620 Premium (2003-2006) | Difference |
|---|---|---|---|
| Type | Sliding gear with dry disc clutch | Partial power shift | — |
| Spec | Allis Chalmers D21 Series II | John Deere 6620 Premium (2003-2006) | Difference |
|---|---|---|---|
| Length | 160in | 186in | ▲ 6620 Premium (2003-2006)+26 in · +16% |
| Width | 91.3in | 90.9in | ▲ D21 Series II+0.4 in · <1% |
| Height | 106in | 112in | ▲ 6620 Premium (2003-2006)+6 in · +6% |
| Operating Weight | 9,502lb | 11,773lb | ▲ 6620 Premium (2003-2006)+2,271 lb · +24% |
| Spec | Allis Chalmers D21 Series II | John Deere 6620 Premium (2003-2006) | Difference |
|---|---|---|---|
| System Type | Not recorded | Pressure flow compensating (PFC) | — |
| Steering Type | Power | Hydrostatic power | — |
| Spec | Allis Chalmers D21 Series II | John Deere 6620 Premium (2003-2006) | Difference |
|---|---|---|---|
| Type | Independent | Independent | Same |
| Speed 1 | 1,000rpm | 540rpm | ▲ D21 Series II+460 rpm · +85% |
| Speed 3 | Not recorded | 1,000rpm | — |
| Spec | Allis Chalmers D21 Series II | John Deere 6620 Premium (2003-2006) | Difference |
|---|---|---|---|
| Hitch Type | Three-Point Hitch | Three-Point Hitch | Same |
| Hitch Category | III/II | II/IIIN | — |
| Hitch Position | Rear | Not recorded | — |
| Hitch Capacity | Not recorded | 16,360lb | — |
| Spec | Allis Chalmers D21 Series II | John Deere 6620 Premium (2003-2006) | Difference |
|---|---|---|---|
| Chassis Type | 4x2 2WD | 4x4 MFWD 4WD | — |
| Drive Type | 2WD | 4WD | — |
| Steering Type | Power | Hydrostatic power | — |
| Brake Type | Band actuated disc | Hydraulic wet disc | — |
| Spec | Allis Chalmers D21 Series II | John Deere 6620 Premium (2003-2006) | Difference |
|---|---|---|---|
| Starter Type | Electric | Electric | Same |
| Spec | Allis Chalmers D21 Series II | John Deere 6620 Premium (2003-2006) | Difference |
|---|---|---|---|
| Coolant | 7.8gal | Not recorded | — |
| Spec | Allis Chalmers D21 Series II | John Deere 6620 Premium (2003-2006) | Difference |
|---|---|---|---|
| Type | Open | Cab (standard) | — |
Category context