1991 GMC Safari

Electrical problem
1991 GMC Safari 6 cyl Two Wheel Drive Automatic 250000 miles

While I was driving down the highway, I lost the radio and all gauges in the dash. The speedometer says I amgoing 100MPH even when parked.
All the other guages are stuck at the place they were when I lost this. I also do not have the PRND21 at the bottom or the odometer reading.
Do you knwo what this might be?
Thank you.
July 12, 2010.

Get the charging system and ignition switch checked out

Jul 12, 2010.