Ok, we're talking 70-72 only. My research says hood pins were optional on early 70 SS then became standard on later 70 SS through 72. We'll sort this out later because in the bigger scheme of things it's just not that important to me. If I'm wrong, I'm wrong, sure it's the first time but who knows, could happen again.
EDIT: One source, read the end of the section on 1970 SS. Actually I really don't care and don't care to piss anyone off. I'm just stating what I've read.
http://www.chevelles.com/shop/ss_ident.html