I think that would be the ballast resistor. If that has been taken out it usually means that there is an electronic ignition in the car. What it does is lower the voltage across the points to about 9 volts so you don't fry them. If you don't have points anymore you don't need one.
Not totally sure on how it all goes together though. The wiring in my 66 Mustang is in terrible shape (bad splices,burned terminals,melted wires, etc..) so I ordered a Painless kit to go in there. Their instructions are really good but the kits are a little pricey. But are well worth it.
done away with the factory voltage regulator
Does this mean that there is an internally regulated alternator in the car?