Bench testing rally gauges

Mattax's photo in post 15 is on the money.
The 5 volts to the fuel guage is internal from it's output, if you apply 5v to a and s on the fuel guage the guage should move.

Looks like Chrysler used the same cardboard on the block of all the gauges so A, I and S are meaningless.

On fuel, S is sender, I is 12v from ignition switch, A is 5V output to the other guages and itself.

On the temp guage, S is the 5V in and I is the sender.

On the oil guage (assumption as I have not seen the back of it) S is the 5V in and I is the sender.

As others have pointed out polarity is not an issue on temp and oil. It is on fuel.