Ron:

Although AM radio reception does indeed suffer from ignition noise, the drone I mentioned in the original post had to do with a rather robust exhaust tone at highway speed.

Mainly I was concerned about overloading something with the generator and a modern radio. I suspected that the wires wouldn't care if the car had a generator or alternator but didn't want to be riding around playing CD's while the charging system was silently suffering.

Thanks for the useful information on the resistors.

Joe in WV