Thanks for the input. I figured it out.
i'll post the info here on this site in case others run across the same problem. While Googling, I did find a few people reporting the same problem.
The problem I found was the key ignition switch is worn out, making bad electrical connection.
At first I wiggled some wires around, damn thing started working. I'm thinking" Hell yeah!"
drove it, all worked fine.
Parked it, come back, temp gauge and Fuel gauge not working. I tried wiggle some connectors, no dice.
So a bad connection to the panel was not the problem.
But I noticed, sometimes it would work, sometimes it wouldn't. The only common thing was....I was turning the key on and off.
So after wiggling the key, just barely, I was able to reproduce the failure mode.
What made it easiest to figure out was getting the vehicle at temp first and watching the temp gauge. The temp gauge response faster than the fuel gauge, so if you do this while watching the fuel gauge, you could miss it. With the temp at normal though, the temp gauge responds quicker. you can see when you loose connection.
wiggling the key, just pushing it forward slightly, made it work, but if it slips back a little, just a very little, it's enough to cause an open.
I hope this helps someone in the future.
I still want to know how that cable disconnects from the speedometer. I was trying by reaching up from under the dash and coming in from behind with my hand. can't see what I'm doing. I can feel the cable turn around easily but I cannot feel how it disconnects.
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