OEM GM original GM part number for the instrument panel dash bulb and socket assembly used in the charging/exciter light circuit is GM part number #25085970
This is the light that shows up when you turn your key forward and the battery light is illuminated. This completes the exciter wire circuit to your alternator. This is a cause of a lot of alternators being swapped out that are good. If you turn your key forward and the RH dummy lights that says Battery doesn't illuminate your charging system will not function. We have bought a few cars over they years where wires were upgraded and the customer just gave up. I have 2 Gold T's because of this little bulb. It has resistors in it also. That can be seen in the base. They are original OEM GM we purchased 80. They will be available until they are not. *Not needed if you have the field fix harness already installed.