The tag is on the inside of the spoiler but the numbers cannot be read. I personally have never come across a 1967 - 1968 NOS Front Spoiler for sale and I keep an eye on camaro parts both on Ebay and Craigslist pretty religiously.
As I stated in my earlier reply, this spoiler is drivers quality, but it is real GM. I would sell it rather reasonable, say $75.00 shipped.