Gagues gone crazy?
 

Driving home in my 67 Mustang (6cyl 200 engine) I notice the temperature gague was at completely hot. I pulled over. Looked under the hood. No water leaks. Opened the radiator cap. No unusual pressure of boiling water. Radiator was full. Tried to restart the car and it started right away then the oil pressure gague went up to completely high. Turned the car off. Oil was full. Started it again and both gagues went to top level again. Started it and it ran fine, no unusual noisess in the engine. Drove it home about 2 miles and parked it for an hour. Started it again. Both gagues still go to top level. The fuel gague is also high, but I just filled the car up so don't know for sure if it involved in this problem. Anyone got any suggestions?

Instrument panel voltage regulator
 

There is a little instrument panel voltage regulator back behind the instument panel. My bet is that has gone bad. On my '66, it was easy to replace and pretty inexpensive.

Rev

Sounds like the constant voltage regulator as Rev described. I had the same problem in that it stopped stepping down the voltage to my gauges, so they all pegged. The root of my problem was the voltage regulator. After I replaced both, everything was fine.