Ok, hold up. There's a lot of misinformation here.
The odometer is digital on our trucks, and is stored in the cluster. It has nothing to do with the PCM, and the PCM does not store mileage.
Repair shops cannot access the odometer.Ford dealers cannot access the odometer. Tuners cannot access the odometer. Nobody on the outside world can access the odometer. When a vehicle needs a cluster replaced, the dealer has to order it from the Ford cluster center. All the info on the vehicle must be submitted to the cluster center along with the vehicle's current mileage. The cluster center then sends a new cluster, with matching mileage to the dealer for install.
Now you could swap in a cluster from a lower mileage truck. But even that is not something the average owner can do. Just like the PCM, the cluster has to be programmed and configured to the vehicle. The cluster also stores the PATS key codes, so it has to be rekeyed as well.
So it's REALLY not likely that one of these trucks has bogus mileage, if it's being sold by a private seller.