OK - This is in a relatively stock car, used for daily driving. Rubber mounts are intact, and using a multimeter, found continuity between the alt. case and engine in several points without the ground wire hooked up. That said, I did upgrade the ground wire years ago to about an 8 gauge wire... would like to keep it that way, if for no other reason than vibration may cause issues down the line ( i drive the thing like a a maniac...). Main point of my original question was to find out exactly WHAT needs to be grounded here, and from all posts to now, it's the case. Simple fix IMHO. Tap and screw into the original ground hole in the case and hook up my HD ground wire going right into the pass. side cyl. head. Am I wrong?