OK, so buying a '98 with 66k original miles. Speedo is way off and here's where we stand (place is having repairs done before I take possession of the car):
tranny not original (from '01... why I don't know)
new sensor installed, but still has issue
with scanner hooked up, sensor reading is off from what speedo is showing (good 60mph + off @ 40mph)
Does it sound like it needs to be recalibrated, or could the cluster possibly be bad? If so, do you have to get a '98 cluster due to the anti-theft that was specific to '98 (along with the special key)? Any guidance would be appreciated! Thanks.
'98 Cobra Speedo on the Fritz 
