I had similar concerns about a 77 Trans Am I had bought a few years ago. When rebuilding it, it became very obvious that the vin had been swapped when the hidden panel stamps didn't match the dash. I found the build sheet and it had the full vin that matched the body stamps. I called the cops out and they ran both vins the national and state database and nothing came back. The way to cop explained it to me was that those databases only go back so far, and if it happened so long ago that it would have been wiped out. The cop gave me the report number so that I could file a civil suit if I wanted to for misleading information or something along those lines. But I don't think that you need to be concerned about going to jail. I wasn't - I just know that if I try to sell that car I'll have to disclose everything that I now know to the next buyer. Call the cops, get them to run it, no sweat....