With my GTO, I have every scrap of paper you could want. The original owner was still local and in the phonebook.
When the car was done, I drove over to his house. His wife came running out saying how she recognized the sound of the car she had heard every day for over 10 years. His family lived in the same neighborhood, and family road trip memories instantly came back. I still have the towing bill receipt from when it broke down on Valentine's day back in the early 70s. They remembered that also
He was reluctant when I offered him to give it a spin around the block, but I wouldn't have had it any other way. Priceless.
I've also been lucky enough to track down original/past owners of other cars. Has always been a great experience.