Sometime back in the 70s, I remember someone saying that's one way to tell if the mileage had been rolled back. Once they were taken apart and mileage changed, the numbers wouldn't line up properly. Over the years, I have seen lots of cars on ebay and on this site where the "low mileage" or "survivor" car odometer is shown in the pictures with the numbers all up and down.
I had several cars that rolled over from 99999.9 back to 00000.0 and started counting again, and the numbers were always perfectly straight.
Now, when looking at cars that are nearly 50 years old, I am more concerned with the condition of the body and interior regardless of miles on the drivetrain.
