I have a 1970 Chevelle SS396 with factory gauges.
The wiring for the AMP gauge was missing from the wire harness. The best as I can tell there was a short at one time because the mylar circuit on the back of the cluster was melted for the AMP gauge wires. I'm attempting to wire it back in. I have an electrical diagram from the service manual but I cannot tell exactly were the 2 wires should mate with the engine compartment harness. My guess is one side connects near the horn relay and the other near the battery at the junction block. Does anyone really know?
Also, How far(how many amps) does the gauge move when working properly? For example when starting the car and when first started?

One side connects to the common power terminal on the horn relay (this is the double terminal with screw connections).

The other end connects to the junction block.

The factory setup also included a 20 ga (orange) fusible link on each end for overload protection.

Thanks for the help. How about the movement of the gauge. Mine doesn't move very much. That is why I was wondering about the wiring. I thought maybe I hooked it up wrong. My gauge may have gotten damaged. Any way to check the gauge to see if it is working properly? I put an ohm meter across it and I think it is ok, but I don't know really how to check it.

Testing :

With the engine not runnig, ignition key on : put on as much as you can, like headlights, blower, brake lights, rear defog, .... The AMP meter should indicate half to full discharge.

To test the other direction : cross the AMP gauge wires at the gauge or jump wire at the points Rod mentioned and do the same as above.

Rob