When you replace a Instrument Cluster is the mileage stored in the brain.
Mileage is not stored anywhere but your cluster, if you are replacing your cluster you need to find a specialized shop who can "adopt" your new cluster. Google can probably help to locate one, as an example in North Hollywood there is "North Hollywood Speedometer". Some cars also have immobilizer data stored in the instrument cluster as well, if your car does not start with the new cluster - you need to teleport the old cluster as well
It is also possible to rebuild your existing instrument cluster. If you look on Amazon they sell the entire kit for a fraction of what a new cluster will cost. It is a fairly easy job and the instructions are decent.
Search Dodge Dakota Questions
Dodge Dakota Experts