| 1971 Grand Prix Speedometer Gear usage Chart | |||||||||||||
| Driven Gear Or Sleeve | Tire Size | Speedometer Adapter | |||||||||||
| Rear End Ratio | Part # | Teeth | Color | F78 X 14 | G70 X 14 | G78 X 14 | H78 X 14 | Model | Ratio | Part # | Color | Trans Code | Drive Gear Teeth |
| 3.23 | 3987920 | 20 | BLUE | X | WT | 8 | |||||||
| Information supplied by George Pearson, taken from a Pontiac Parts Book | |||||||||||||