Not much other then giving you some info on any possible codes. Carfax is a good place to possibly find the current mileage. I think there is a 10 year law and if the truck has changed hands the mileage has to be reported. As far as a programmer goes if the truck has been run for so many miles without a chip or tuner then they would have to look at the pistons to tell if it had one or not. What are some of the mods on the truck now?