I'm pretty sure it is illegal in all states. Once the car passes 60+ years, though, I don't think there is much interest in prosecuting for it. Here in Texas, the title application has a block for "odometer exceeds the mechanical limits of the car". We always check that on collectibles, and I think it pretty much means the car is too old to worry about the odometer reading. In Red's case, if anyone gets huffy about the odometer change, he just has to say it was necessary to repair the speedo. The key is to not attempt to lie about the car's mileage.