Classic cars....unlike most firearms, have provenance up the gazoo if you look, particularly "one-off" stuff like Shelby's. There IS a Shelby Registry, and if the VIN ain't on it, it's time to start walking.

We get into the same thing with Yenko Stingers in the Corvair World. It's a fairly easy car to "replicate", and the difference in value between the "real" and "Memorex" version is 1000% give or take! Thankfully, real Yenko Stingers are easily identified by the GM/Yenko VIN series.