led as alternator functioning lamp

I am working on a Kit car. It's supposed to be a 1930s vintage but I am using a 1969 VW beetle donor, 12 volt. The original vehicle has a lamp for the generator on the dash, like a warning lamp that I am told stayed on when the generator was ON, so it's lit while driving. I have the dash with the light cover and was wondering how to wire an LED as a warning lamp for the Alternator, ON when the vehicle is in operation. What current limiting resistors would I need for the 12V system? Is this possible? What other circuit safety devices would anyone recommend? I was going to put this on a fused circuit but the particulars are open to suggestion.

ANY suggestions would be gratefully accepted, at any level (I am new to electronics).

Thank You.

The beetle alternator would probably require a Charge Lamp to ensure charging, so I assume you are keeping that. The "charging ok" indicator would simply be a 12V light/LED connected from the negative side of the charge lamp (ie, L output from the Beetle's voltage regulator) to GND. Hence a LED with whatever dropping resistor is required for 12V (typically around 470 Ohm). Normally however charging is indicated by the Charge Light NOT being on. (Very different to the 1930s when charging was unreliable and required "positive confirmation".) But some use an additional charge-ok lamp to guard against a blown (not) Charge(ing) Lamp - especially in vehicles that do not have other dash lamps "ignition-on tested" by the Charge Lamp circuit.... Not being one to ramble, you'll have to ask for more if that's unclear.