chances are its a scam...however, remember that in the 80s Shelby made quite a few turbo cars when h was working with Dodge...also some 1st gen mustangs were supercharged, shelby has always been fond of boosting cars...so it is a possibility, but I myself would need to see some documentation to prove it...also possibly a call to shelby for confirmation that such a thing existed, i would also want to see the turbo manifold....cast iron is a good indication of a factory manifold...a header type manifold might indicate custom fabrication(not to say that shelby doesnt make custom parts, but he has access to tooling for cast iron pieces)...regardless, most shelby cars have a plaque, or at the very least a signature on the dash somewhere