68 Turbo with electrical problem

[cbxmike]

I recently had a mechanic with superior skills (superior to mine) that I know and trust look at my charging problems. He did find corrosion on the main bus bar behind the CB's and cleaned and repaired. Replacing the bus bar is probably the next action. In fact the alt field CB, I think that's what it's called, was not making good contact. We thought we had possibly found the smoking gun so to speak. After cleaning and correcting the bus issues we ran both engines and not getting any charge now from either Alt on either VR. Just battery voltage. Oddly enough, the alternators only have about 300hrs on them. So we checked the voltage through the alt switches. That was good. Then the voltage to both VR,s. That was good (batt volt). So the next was the field voltage at each Alt. That was the same (batt voltage). My question is this: Is it more likely to have two failed VR's or two failed Alt's? Or better stated, is it possible that the VR's are both bad causing no output from the Running alternators even though we get (batt voltage) from each Alt field test? Does getting batt voltage at the alt field yet no output from the alternator while running confirm bad alternators? I know, that was more than one question.