I recently purchased a 2003 Mach 1 with the automatic transmission. I noticed within a few days that I seemed to be going much slower than the speedometer was showing. I checked the speedometer with my GPS. At 40 mph on the GPS I am showing 46 on the speedo. When the speedo. shows 75 the car is doing 65 mph. Went to a transmission shop and put it on the rack. We found a Autotrans, Inc. Recalibtrator attached to the frame. It was unplugged. We plugged it in and tested again but the reading was the same. I am guessing that the previous owner had the gears changed in the rear end.I have no instructions for the recalibrator. Went on line and found a web address but it is underconstruction. I tried the phone number listed in Alberta Canada but it is no longer in service. Does anyone have any suggestions? I am trying to locate a speedometer repair shop in the Cleveland Ohio area but no luck so far.