Speedo Drive Gear 18- Tooth GM 250C/350C/375B

The Speedo Drive Gear 18-Tooth GM 250C/350C/375B is a precision speedometer drive component engineered for General Motors automatic transmissions, specifically the Turbo 250C, 350C, and 375B platforms. This small but critical gear synchronizes your speedometer reading with actual vehicle speed by converting transmission output shaft rotation into calibrated pulses for your instrument cluster. Whether you're restoring a classic Chevy, rebuilding a transmission, or diagnosing speedometer inaccuracy, this OEM-spec replacement gear ensures your speed readout remains true to your actual road speed.

The 18-tooth configuration is purpose-designed for these specific GM automatic transmissions, where gear tooth count directly determines the ratio between transmission speed and speedometer needle deflection. A worn or damaged speedo drive gear produces erratic needle movement, pegging, or complete instrument failure—common issues in high-mileage or modified vehicles where transmission internals see stress. TCI's replacement gear meets factory specifications and restores accurate odometer and speedometer function without requiring recalibration or electronic compensation, making it the reliable choice for transmission builders, mechanics, and enthusiasts who demand precision.

This gear is essential for anyone performing a Turbo 250C, 350C, or 375B transmission rebuild, swap, or repair on vehicles from the 1960s through early 2000s GM lineup. Installation requires removing the transmission output housing and replacing the worn gear—a straightforward process during a rebuild but critical for post-work accuracy. Mechanics and DIY restorers benefit from stocking this compact, lightweight component as a wear item, ensuring every rebuilt or serviced transmission delivers correct speedometer performance from day one.