In the early 70s, I'm sure in most places you could see an ebody pretty regularly on the road. Maybe every day you might run past one or two. Today, I can drive around my town for months without seeing another. Back then they were daily drivers. Today, theere are not only a lot fewer of them, virtually none are daily drivers.
With rust, accidents, engine failures etc., I would bet the bank that half of them didnt survive their first ten years, much less 40.