Where is the mileage stored on a 2nd gen MarkVIII

[tonybrooklyn]

Just as the title says is the mileage stored on the odometer. Or is it stored in the cars computer. Are the speedometer clusters just plug and play from one vehicle to another. Or is programming at the dealer required? Did a search found no results.
Thanks in advance as always for you time and help in this matter.
Best Regards
Tony