I purchased this truck from a small dealer in KY. It is a one owner vehicle, no accidents. Completely stock, correct tire size and no evidence of rear gear change. Private shop found discrepancy with speedometer reading 80mph when it was actually going 60mph. Anybody have any suggestions or ideas as to what might be the issue? Also this my 3rd RAM SRT-10 RC ,never had any problems with these trucks except for the camshaft recall when my 2004 was new. Owner of the shop is going to try to find the problem this coming Monday.I checked and both safety recalls on the driver and passenger side air bags were completed.