The rest of the story:
FiFiero put me in touch with the transmission shop that had her car. They had been working for about 2 days trying to find the solution. He searched, found and bought a wiring schematic for the car. We discussed the circuit from back to front and he said that he had traced the speedometer circuit. He had removed the VSS and verified the VSS and gear was good and getting a signal to the harness underneath the left side of the instrument cluster.
I suggested he clean the contacts and spring the harness contacts to make better connection with the instrument pod. That didn't fix the problem. I asked if he'd checked the fuses for the instrument cluster and guided him to the fuse block and the correct fuse.
He checked the gauge fuse and verified that it was good. He also checked all other fuses and they were good. I asked if the speedometer moved when he turned the ignition on and he said that the speedometer was sitting at about 45 mph even with the ignition on, so to me this said that there was no power to the speedometer yet everything else in the cluster was working. We agreed that the speedometer had died.
I packaged the instrument cluster and was ready to take it to UPS. As a last stab in the dark, I called and asked him to go back through and check all the fuses again. He reported back they were all good, except that the radio fuse was removed because FiFiero had experienced battery drain due to a bad radio.
Now we all know the Fiero has some funky combinations when it comes to circuits. For instance, the cruise control is fused through the radio circuit. So, I asked that he insert the radio fuse and turn on the ignition.
Well, the speedometer immediately dropped to Zero. I waited while he put a jack underneath the rear and lifted the wheels off the ground. First I heard the engine start and then I heard the joy in his voice. "That's It! It's Working!"
That's good. No that's bad. No that's good.
The first good--We got it working with 2 days labor and a 50 cent part.
The bad--I lost a $60 sale of an instrument cluster.
The second good--I sold her another radio for $60.