Ok, today I went on a ground hunt. I started in the trunk, I knew there were two in there. They were both painted, so out came the Dremel, and I stripped to bare steel.

Under the hood, found a ground front driver side, same thing. Then, I believe I found the culprit. Just behind the air cleaner, just below the main chassy ground which I already did, is a double-wire ground, same same.
Now the volts Guage started working, very nice. Fuel guage still inop, pegged past full. A quick check with a 9V battery shows the Guage good, so the sending unit is now suspect. A light spray of clear matt enameling the ground lugs so nothing rusts, and the ground issues should be gone for good.

I fully disassembled the Guage cluster, cleaned everything. For the clock I alternated blasts of contact cleaner and some quality spray lube. Cleaned the solenoid contacts with fine emery cloth. For the speedometer, just a couple drops of turbine oil in the input shaft.

It appears the mylar "circuit board" suffered failure due to lube leaking from the speedometer or the rotary shaft. Cleaned it up with contact cleaner and Qtips. If I can remember to get some superglue I'll adhere the traces back into position, and reassemble.

It's interesting how these were made. Cardboard tubes for the indicator lamps, some is screwed together, some has metal tabs bent over. It is rather prominently stamped with 1126 74. Late 74 manufacture? Probably correct for the 75. Not much sign of previous hands in the dash other than the radio, whose installation is on par with the half assed work which is becoming more and more evident in the interior.

I hope the major mechanical was done to a higher standard.