1971 Pontiac Tempest & GTO Speedometer Gear Usage

Information supplied by George Pearson
1971 Tempest & GTO 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 F60 X 15 Model Ratio Part # Color Trans Code Drive Gear Teeth
3.08 3987919 19 NATURAL X X X             WT 8
3.23 3987920 20 BLUE X X X             WT 8
3.31 3987920 20 BLUE   X X             WO 8
3.31 3987921 21 RED         X         WO 8
3.55 3987922 22 GRAY X X X   X         WT-WO 8
3.90 3987921 21 RED X X X   X     6478549   WT-WO 8
4.33 3987920 20 BLUE X X     X     6477964   WT-WO 8
4.33 3987920 20 BLUE     X         6478548   WT-WO 8
Information supplied by George Pearson, taken from a Pontiac Parts Book