If your voltage regulator is working OK at the moment and the earth is good I suggest you add another earth strap between case mounting bolt and the chassis earth bolt. Cheaper than buying another regulator "just in case". My car has all this from manufacture and (fingers crossed)it has been OK. I suspect that all the problems have been caused by poor earths and chassis to case bonding rather than duff regulators. You may also notice in the photo that one of the rubber mounting "Bobbins" has sheared. This is the 4th one to go in 1700 miles. Another temp repair carried out until it gets replaced soon, not an ideal installation.
