On my 69 I have a ground strap at the forward end of the Tranny to the body. It uses a tranny bolt on one end and body on other end, just to the right of the speedo connection under there (looking from back of car to front).
I also have developed a generator light that increases with intensity as RPM's increase. At higher RPM is actually blinks at a steady rate like it is being timed by a relay opening and closing.
Very dim at low RPM.
I had my engine out to do the sound pads and all wiring went back in based on digital photo's I took before removal.
Craig
www.bay912.org