Thanks so much to those of you who devote time to answering the questions of confused "restorers". This site has been worth much more than the price of admission. The fuel and temperature gauges on my '71 have small plastic "slabs" connecting two of the terminals. In fact, the temperature gauge has two of these "slabs" arranged in a cross (across one another). One of the "slabs" on the temperature gauge is broken in two places. What are they and do I need to replace the broken "slab" and if so,where to get it? Also, they have markings on them like it may make a difference which end goes where. Does it?

Are you talking about the base that the terminals are riveted to? If so, as long as a connection isn't interrupted, i.e., rivet intact, you should be ok. If I'm not in the right place with you, and the gauges are still out, can you email a picture of the piece you're describing?

Sorry, I can't send picture yet. What I'm referrring to is a plastic rectangle measuring 1 3/8 by 1/2 by 1/8 inch thick. They go under the nuts on the threaded studs which retain the spade terminals on back of the gauges. The ammeter also has one (besides the fuel and temp gauges). It looks sort of like an isolator, but a couple of them have copper where the nuts hold them down like it may be some kind of a shunt with resistor wire inside.

I think you're on the right track with the resistor idea. I believe that the gauges have resistors placed on them to be able to properly calibrate them with their respective sensor units. I could be wrong, but I think this is what you are looking at on your gauges. Take one off and check it with an ohm-meter to verify.

Since its a Corvette, I should expect the most complicated possible design. Turns out that some of the "slabs" are resistors and others are isolators. The isolators are solid plastic and keep gauge terminals from grounding to the cluster body. The ammeter has one of those. The fuel gauge has an isolator, then the spade terminals for the wiring harness, then the resistor slab which provides about 86 ohms across the terminals all held to the gauge mounting studs with nuts/washers. That much I figured out. Now the problem is the temperature gauge. It has 4 mounting studs and 3 of them hold the spade terminals for the wiring harness. There is one resistor and one isolator slab and their shapes indicate that they mount crossways to each other. The wiring diagram shows the middle spade terminal to be a ground (but not through the cluster body). Can anyone tell me whether the resistor goes across the top and bottom spade terminals vs the middle spade terminal and the otherwise unused 4th mounting stud?

Upon further study, it looks like the physical layout of the various parts on the back of the temp gauge is best without the resistor thingy. Does a temp gauge need one?