This 39 tooth short shaft speedometer gear is designed for Jeep Wrangler YJ, TJ, Cherokee XJ, and Comanche MJ models equipped with NP231 transfer cases. It is used to correct speedometer readings after changes to tire size or axle gear ratio. The gear installs directly into the transfer case speedometer housing and restores proper speed readings by matching your setup to the correct tooth count. Refer to the speedometer gear chart shown in the Amazon listing to select the correct gear for your tire size and axle ratio. Proper gear selection depends on actual tire size and axle ratio. Tire sidewall measurements are often inaccurate, so you must verify your true tire height before ordering to ensure correct gear selection. Replaces 52067639, Interchange 18760.27 Fits: Jeep Wrangler (YJ) 1993–1995 w/ NP231 Transfer Case Jeep Wrangler (TJ) 1997–2006 w/ NP231 Transfer Case Jeep Cherokee (XJ) 1991–2001 w/ NP231 Transfer Case Does NOT fit Rubicon models