| 1970 Firebird Speedometer Gear usage Chart | |||||||||||||
| Driven Gear Or Sleeve | Tire Size | Speedometer Adapter | |||||||||||
| Rear End Ratio | Part # | Teeth | Color | F60 X 15 | F78 X 14 | F70 X 14 | E78 X 14 | Model | Ratio | Part # | Color | Trans Code | Drive Gear Teeth |
| 3.31 | 3860344 | 21 | RED | X | X | WB | 8 | ||||||
| 3.31 | 3987920 | 20 | BLUE | X | WB | 8 | |||||||
| 3.31 | 3860346 | 23 | BLACK | X | 1563872* | WL | 8 | ||||||
| 3.31 | 3860347 | 24 | YELLOW | X | 1563872 | WL | 8 | ||||||
| 3.36 | 3860344 | 21 | RED | X | X | X | X | WB | 8 | ||||
| 3.55 | 3987920 | 20 | BLUE | X | X | 6451999* | WB | 8 | |||||
| 3.55 | 3860342 | 19 | NATURAL | X | 6451999* | WB | 8 | ||||||
| 3.55 | 3860345 | 22 | GREEN | X | X | WL | 8 | ||||||
| 3.73 | 3860344 | 21 | RED | X | X | 6451999* | WB | 8 | |||||
| 3.73 | 3987920 | 20 | BLUE | X | 6451999* | WB | 8 | ||||||
| 3.73 | 3860346 | 23 | BLACK | X | WL | 8 | |||||||
| 3.73 | 3860347 | 24 | YELLOW | X | WL | 8 | |||||||
| NOTE: All adapters require key part number 867209 | |||||||||||||
| Information supplied by George Pearson, taken from a Pontiac Parts Book | |||||||||||||