It goes to the block. Originally it went to a stud on the rear of the block but the location isn't critical. Its a ground. You can never have too many. Find a convenient stud/bolt that it will reach on the block. You can't really see much in these images but here they are anyway.
Thank you!! I did find where it broke off. Cleaned it off, put a new connector on, reattached. Still can't figure what it is grounding. However, so far, my battery light isn't flickering on and off anymore. New alt and six tests on it and batteries. Batteries are always 12.42. So so far, so good.
Would like to do more grounds, though. Anyone know a dummies or mechanically not-inclined guide to adding grounds?
It's providing a ground path from the body back thru the engine (where the battery ground cables are connected) and back to the batteries. There's no need to add more as long as you have the ones the factory put there.