reproduction fender tags legal?

It's not the reproduction tag that is illegal it's using a reproduction tag to misrepresent the car as in a future sale. That is fraud and you could be charged with such, or sued for damages.
exactly. but, if you have a car, with no broadcast sheet or window sticker, and only a fender tag that matches all the VIN # information, but has a slew of options, that did not come on the car, unless you can prove the tag is a fake, you cannot prove otherwise(in most cases) unless it has been registered with a registry and/or with a broadcast sheet /window sticker.fraud has happened,is happening,and will continue to happen, unfortunately.