After mine was stolen, I got a call from a guy in Washington State that bought it off a pop-up lot (15 days later) with different vin numbers. When the title didn't show up 30 days later he went to the lot and the whole operation was gone. He took it to a GMC dealership and they ran the VIN with a computer hooked up to the truck and it didn't match. He then went to the police station and found our police report.
Before finding this out, I assumed they were just chopping these trucks up and selling the parts, since most are interchangeable with other years and models.