[patrickt]

Alternators usually have a ground connection, labeled as such, on the back just like BATT, FLD, or STAT. But not always. And they usually take their ground from their bracket bolt to the side of the block. Snap a pic of the manufacturer's label on the Alternator. You know, like Delco-Remy Model #12345, etc.

And you can't really tell just by looking at a ground whether it's any good or not, or whether you need another one somewhere else. You have to measure the current and do voltage drop tests, which all are very easy to do once you learn how. FWIW, I have more than one ground and continued adding grounds until the current that was passing through each ground cable was down to an amperage level that I liked to see. On the other hand, the car ran fine, and the lights and fans worked fine taking their ground connection off the frame, with only a single 10 gauge ground wire from the head to the firewall/frame. But on the third hand, my amp gauge needle started wavering after a good 10+ years of never doing that. It was cured by adding an additional ground wire to the voltage regulator case to supplement the little ground wire that was in the harness.