Seen them on points distributers as well.....So not just electronic dizzy's....From crappy memory, it was used as a radio suppressor....You would get a weird noise through the speakers, when the car was running with the radio on, so it was used to prevent this....Not real successfully IMA, but that was the theory behind this part
I only said electronic as I know it goes on the positive side of the electronic system I haven't seen a commodore with points since I was a kid. i assume it also goes on the positive with a points system but would need to look that up.