Well when the speedometer stops working, generally it's speedcable (which we don't have since it's electronic), VSS or the gauge cluster itself.

If the rpm / speedometer is both out then i'd try the gauge cluster but in this case, i'm guessing it's the vss.

*edit* here's Vss solde for $30 http://www.homemadeturbo.com/forum/i...?topic=70770.0