Even if there were novels on Cassette Tape, I was still in the Navy, and there's no listening with headphones at sea (safety) so there's no audiobooks. Read, or starve.
So, my first Audiobook Novel wasn't until 2011, when I took Tana French's "In The Wood" with me, on a drive to Florida. I was anxious waiting at a hotel, to get back to my book, on the road. Great book BTW, she (Tana French) became my fave series of audiobooks after that.