Car is overcharging. Please help!!

by a 2 wire alternator, you mean you have one large wire and one small one? If that is the case, it could very well be a bad ground on the regulator. On the older ones with one small wire going from the alt to the reg, the reg needs a real good ground because that is how it measures the voltage and knows how much current/voltage to allow through. If you have a bad ground there, it will overcharge.

Also, make sure you have a good ground from the engine to the frame/body.