If this is like the 97 E420 / E320 W210 body, it has a 93C53 serial EEPROM on the back center of the instrument cluster PC board. This should hold the total mileage and trip mileage. The MCU might have a EEPROM area but I haven't looked yet.

I'm going to desolder the 93C53, read it, put back in cluster, reset trip , read again. Will also add miles to total and see if it changes.

The engine computer may or may not hold mileage, I'm not sure. ( It is likely to hold the VIN )

There is a failure prone ribbon cable that attaches the LCD to PC board, some Euro sellers have these cables. Toshiba makes the LCD drivers T7932 and T7933 I haven't pulled any tech sheets yet.

Your most direct route might be to get a cluster with close miles. Try car-part.com for a nation wide salvage yard inventory search.