Like Stan says, all the clones copied the Linda Vaughn car and used the white bucket seats to mimic that promotional car. There is no way to confirm that there was more than one of those promotional cars made. If the body code plate on the car you are looking at shows a CM27U0C starting VIN, that would also indicate a convertible that was factory (if the body code plate looks original and not a fake copy) with the 440HP engine, but the bucket seat code should also be there for a real production 300Hurst, which would be M6T5 and usually there is an A12 code on the plate as well. It should be obvious if the body code plate has been reproduced and is fake, but a guy trying to pull off a real Hurst production convertible will do their best to make it look real. I have never even seen a photo of a claimed production Hurst convertible that had the production interior and then if there was one, it would probably have a brown boot color to match the interior, not a white one.