Is my Voltage regulator bad?

Hello, I've got my customers 70 Dart 340 swinger back at the shop. I had previously reassembled this car from a rotisserie restoration. Once I got all mechanical together, and got it running, I noticed that the Alt. was overcharging ( I showed a 1.2 volt loss at the blue Alt wire). Well the car left my shop to go to the body shop to reassemble the sheet metal. Before he took it I unhooked the green wire on the alt. so it wouldn't fry the battery while the motor was running.
So first thing I do is start looking for voltage loss in the harness, and I noticed that I now only show a loss of .12 volts at the blue alt wire. So far sounds great eh? But wait... I forgot to hook the green wire back up.
So as you might have guessed, i'm back at the 1.2 volt loss again with the green wire attached.
As the topic says, Is this a bad voltage regulator,or am I tearing the dash board apart on this thing?
Thanks in advance...Pete