How to determine the difference.

Is someone trying to sell you items claiming they are NOS? If that is your yellow Cuda, you've got your self a really nice car

Inspector71 thank you for the compliment, the yellow Cuda I've owned since 1988.

Always panning through the parts for sale auctions out of curiousity just incase something peaks my interest, and came across a few different items being sold as NOS but there's no way to verify, due to no packaging or part numbers, just wanted to see others thoughts about this, NOS is expensive and can one really take the sellers word on it. I believe most on here would not.