Originally Posted by SpectorV
the VSS sensor is what he is talking about above (at least on 99 ups its called that) on pre 99s there is a speedo gear. Check that sensor, if its bad... but when mine had issue the speedo didnt work either.
i put a t 45 in my 03 gt and the issue was my tach still worked but my speedo was off the gear on the vss was the wrong one. but there was an electrical plug and a cable plug in on it. the cable plug is for the speedo and the electric plug is for the tach and the odometer and trip meter. at least im pretty sure