I am considering buy an '05 supercrew with 97K on the odometer. The engine was "tapping", but when the guy tried to fix it, he was told the motor was unrepairable. He put a new ford crate motor in it (He has papers on the engine change). My questions you guys are: what do I look for in the paper work, will it happen again, what should I look for concerning the truck? The truck drives great and looks great. Thanks for your advise!!!