Here's how I had the battery grounds hooked up. I put that wire there myself because the car didn't have a battery when I got it and I wasn't sure where the ground should go. There was already a hole there, and it was convenient. I just found a bolt that would fit the hole, and away I went. Many years later I learned that hole was for the AC line clip. The AC lines, compressor, and condenser had already been removed from my car when I got it.
