I have seen this cable you speak of. I noticed it when I took my rear seat out a couple of months ago. It’s located behind the backrest of the left passenger. in the area of where a seated passengers left shoulder would be. the cable or wire have a loop in one end which is tied up around a rubber hanger. I think I have a picture of this, but I’m not sure how to upload it on the forum. perhaps it’s only on the -87 models, since mine is that year as well.