voltage regulator problem

well, I feel real stupid asking about an ECU as a regulator. I have never seen one. This car had one missing when we got it and my Duster has a MSD 6AL box on it so I am trying to find out why a 2 prong regulator now has 5 prongs on it. the regulator and the ECU was gone inside the compartment.If the ECU will hold out for a little while, when we put the 340/4spd. in it we will most probably go with a MSD box. I just want to hear this puppy run and then tweek whats needed. I am going to have to get another 2 bbl carb and a gas tank before I crank it though. They are nasty. Thanks for the info,Bill