1997 Astro AWD 171K miles. Since I've owned this over the past couple of years, the speedo has been getting steadily more and more overly optimistic on the indicated speed. Lately, it reads 85mph when I'm doing about 35mph. As much as it's an ego boost to bury the needle past 100mph when tooling along the freeway at 60, it's a real pain trying not to get dinged for speeding in town as I have no idea how fast I'm really going. I first thought it might be the Vehicle Speed Sensor (VSS), but the transmission shift points are normal and the odometer is spot-on. Both of these are driven by the VSS so my guess is the VSS is fine. I think it's either the output signal from the computer to the speedometer, or the speedometer itself. The 97 uses an analog needle but there is no classic spinning speedo cable; it is an electrical signal from the computer. I sort of doubt it's the computer since everything else seems fine. I suspect something in the speedo head itself, like a bad ground? I've done some forum searches and come up with a few hits of others saying their speedo is also reading way high, but I haven't come up with any solutions. Any idea? Thanks