I had the pleasure of meeting Irv at a classic car/Volvo meet and I was told, by Irv, that the car is original. It has not been in an accident that would involve major body repair.
The main point he made to me was that he BABIES this car. He drove like an old man even when the car was new. He imagines the proverbial "glass of water on the dashboard". He babies the drivetrain and sticks to an ironclad maintenance policy. He cleans the body to avoid rust and generally takes "ultracare" of that car. That's why it hit this milestone.
He did not set out to do this. It just occurred to him that it may make it after the first 500K.