If it is a t-5 the speedo gear is located on drivers side of the tranny toward the back (output shaft). You will see the speedo cable and an electrical connector there. remove the small bolt and pull the assembly out from the transmission. Remove the metal c clip holding the old speedo gear on (keep metal c clip for reinstall) And reverse the operation to install the new gear. don't force the new gear in as you may break off some teeth. Not a hard operation at all. Good luck.