Some years back I was speaking with a wrecking yard owner who was buying the diesels at city auctions and what not. The trucks looked pretty beat up, so I asked him where the profit was.

He told me that the Cummins was easily outlasting the bodies and that no matter how beat up or rusted out the truck was the engine was still good. He could easily sell them to those who had taken better care of their trucks and finally worn out the engine.