| 1966 Tempest & GTO Speedometer Gear usage Chart | ||||||||||||
| Driven Gear Or Sleeve | Tire Size | Speedometer Adapter | ||||||||||
| Rear End Ratio | Part # | Teeth | Color | 6.95 X 14 | 7.35 X 14 | 7.75 X 14 | Model | Ratio | Part # | Color | Fitting & Seal Assy | |
| 3.36 | 3860342 | 19 | NATURAL | X | ||||||||
| 3.36 | 3860341 | 18 | BROWN | X | ||||||||
| 4.33 | 3860329 | 20 | YELLOW | X | ||||||||
| 3.90 | 3860344 | 21 | RED | X | X | |||||||
| 3.90 | 9780522 | 18 | GREEN | X | ||||||||
| 3.55 | 3987920 | 20 | BLUE | X | X | |||||||
| 3.55 | 3860342 | 19 | NATURAL | X | ||||||||
| 3.08 | 3870351 | 17 | PURPLE | X | X | |||||||
| 3.23 | 3860341 | 18 | BROWN | X | ||||||||
| 3.23 | 3870351 | 17 | PURPLE | X | ||||||||
| Information supplied by George Pearson, taken from a Pontiac Parts Book | ||||||||||||