I had an 8 track in one of my cars, years ago. Then I remembered they were total garbage and the tapes sucked, broke apart, got eaten up, had piss poor sound - you'll quickly find a new use for coins and match books just to get the sound quality to even come out half way right. Not to mention you had to wait forever to hear your favorite song come on unless you happened to either have blank self made tapes or your player had a fast forward on it...not all players did. Oh yeah...and the ever CLICK-CLICK right dead in the middle of a song. But the best thing about them was being able to take your music and listen to it in the car.
I'm not sure when they stopped putting 8 tracks in GM cars....probably 1982 as I've only seen them on the old 2 shaft styled radios; 1983 or 84 they started doing the din and a half styled radios.