Key Features
- 21 tooth count with red color coding for quick visual identification
- Precision molded for accurate speedometer calibration after gear ratio or tire size changes
- Fits GM T5, Muncie, Saginaw 3 and 4-speed, Turbo 350, Powerglide, and 200 transmissions
- Commonly used in Camaro and S-10 T5 five-speed applications
- Direct replacement for GM part number 3987921
- Measures 2.25" length x 0.305" shaft diameter x 0.800" wheel diameter
Description
When you swap to a 5-speed or 6-speed transmission or change your rear axle ratio, your original speedometer driven gear won't match the new final drive setup. The result is a speedometer that reads high, low, or somewhere in between -- never accurate. This 21 tooth red GM speedometer driven gear provides the correct tooth count to dial in your speedometer after drivetrain modifications.
This precision molded gear fits a wide range of GM manual and automatic transmissions, including the T5 five-speed, Muncie and Saginaw 3 and 4-speeds, Turbo 350, Powerglide, and TH200 units. It's a popular choice for Camaro and S-10 T5 conversions where maintaining an accurate speedometer is essential for daily driving and legal compliance. The red color provides instant visual identification of the 21 tooth count, making gear selection straightforward when calibrating your speedometer setup.
This gear is a direct replacement for GM part number 3987921. Simply remove your existing driven gear from the speedometer housing, swap in the correct tooth count for your application, and reinstall. Pair this driven gear with the appropriate drive gear on your transmission's output shaft to achieve accurate speedometer readings for your specific axle ratio and tire combination.
Kit Includes
- (1) 21 tooth red speedometer driven gear