see if they have done heads , oil cooler , egr valve injectors etc. I just bought an 05 with 201,000 3 mounths ago and love it. The best thing u can get if u get the truck is and edge insight money well spent could of saved my grandpa sevral thousands dollars. Keeps track of your oil temp and coolant temps so they don't get more then 15 deg apart, and a bunch of other things it does. best thing for the 6.0L love mine don't regret it one bit good motors just don't take maintance neglect