Back when I was working for Ma Mopar 2007-2008 we were told the mileage was stored in the ECM, cluster and one other module. If you replaced one module, the other two had to agree and the new module would receive the correct number of miles.
I wanted to change the standard instrument cluster in my '08 Magnum to one that had EVIC and was told by "everybody" that the foreign cluster would be rejected, the engine wouldn't start, etc. After installing a wrecking yard cluster with EVIC everything worked as before but the odometer mileage was way off i.e. my car had 92K and the replacement cluster had 148K. I purchased an MT401 programmer from OLDPROG Technology and reset the odometer via the OBD port to match my true mileage.
Only hitch was the steering wheel buttons wouldn't work until activated using the Appcar app...ditto for the Homelink that I also added. Been through California Smog Check several times since then and no anomalies were detected. Smog Check on my year is done totally through the computer, no tailpipe sniff.
