| 1968 Tempest & GTO Speedometer Gear usage Chart | ||||||||||||||
| Driven Gear Or Sleeve | Tire Size | Speedometer Adapter | ||||||||||||
| Rear End Ratio | Part # | Teeth | Color | G70 X 14 | 8.25 X 14 | 205R X 14 | 7.75 X 14 | G77 X 14 | Model | Ratio | Part # | Color | Trans Code | Drive Gear Teeth |
| 3.08 | 3870351 | 17 | PURPLE | X | X | X | FO | 7 | ||||||
| 3.08 | 3860341 | 18 | BROWN | X | 777-S | 1.1250 | 540474 | NONE | FO | 7 | ||||
| 3.23 | 3870351 | 17 | PURPLE | X | X | X | X | X | FO-FS | 7 | ||||
| 3.36 | 3860341 | 18 | BROWN | X | X | X | X | FO | 7 | |||||
| 3.55 | 3860342 | 19 | NATURAL | X | X | X | X | FO-FS | 7 | |||||
| 3.90 | 3860344 | 21 | RED | X | X | X | FS | 7 | ||||||
| 3.90 | 3987920 | 20 | BLUE | X | FS | 7 | ||||||||
| 3.90 | 9780522 | 18 | GREEN | X | X | X | FT | 6 | ||||||
| 3.90 | 9780523 | 17 | BLACK | X | X | FT | 6 | |||||||
| 4.33 | 3860329 | 20 | YELLOW | X | X | FT | 6 | |||||||
| 4.33 | 9781826 | 19 | ORANGE | X | FT | 6 | ||||||||
| Information supplied by George Pearson, taken from a Pontiac Parts Book | ||||||||||||||