It will pickup at whatever mileage is on the new odometer. You will need to make a note of the mileage on the old odometer in case you decide to sell the truck.
“Somebody has to speak for these people. Y'all got on this boat for different reasons, but y'all come to the same place. So now I'm asking more of you than I have before. Maybe all. Sure as I know anything, I know this—they will try again. Maybe on another world, maybe on this very ground swept clean. A year from now, ten? They'll swing back to the belief that they can make people...better. And I do not hold to that. So no more runnin'. I aim to misbehave.” Mal Reynolds Serenity/Firefly