alternator for 65 dodge dart

You're safe if you keep it below 50 amps; higher than that and the existing wiring will not tolerate it. Do not get a "remanufactured" alternator from a parts store; they're junk. You can get a brand-new Chrysler 46-amp alternator from Old Car Parts Northwest, 206-300-1083. Guy's name is Ray; tell him Dan Stern sent you. The ones he has are '70-up type with two field terminals; these are easily adaptable to your '65 -- all you have to do is connect either of the two field terminals to ground and connect your car's one and only field wire to the alternator's other field terminal.

Get a good new voltage regulator, Standard VR-128 or NAPA Echlin VR-1001. Run a ground wire, 14-gauge, from the "GRD" hole on the back of the alternator to the voltage regulator base and from there to the battery negative terminal.

See here for charging system/wiring upgrade info.