What kind of Hooker headers are these?

I know they are for big block Chevy, my question is more about the era these headers are from, don't look like the new ones and I can't find the exact product code which appears to be R2227K. Would be cool to find out if these are original headers for the 60's or 70's.

http://imgur.com/a/aMOrd

Having a hard time uploading on this website, keeps failing, so here is a link to an album. http://imgur.com/a/aMOrd

they are made of unseenium .. they are invisible ..very rare material ...hard to find ...