Blowing voltage regulators
This field wire could have caused a short if it contacted the alternator housing even if it still had the connector cover on it.
The field terminal on the left must be isolated from ground.
It connects to a carbon brush. The brush holder is non-conductive. These are easy to take out and check.
If the ground brush is removed first (on right in above photo) there should be no continuity between the field terminal and the housing.