I'm not sure where the mileage information is stored in that year. It's probably in the cluster though. If you can't find any other mention of this issue, you might consider finding a used cluster. The new ones are pretty expensive, with an list price of $1200 to $1400 for the part depending on the option package of the car. You might also search for "instrument cluster repair" and talk to them to see if your issue is repairable. Here's one I found, but I don't have any experience with any of the services.
https://atlantaspeedometer.com/sign-in. ... ort=normal