Definitely legit vintage. Not a concert tee but more than likely from a 70's headshop like this photo where they sold blacklight posters, incense and t-shirts like yours. The Russell tag indicates that era and that it was a plain black tee purchased probably in small quantities and printed on before licensing became a billion dollar business.
![Image](http://img163.imageshack.us/img163/7004/mistymountainheadshop19.jpg)
Misty Mountain Record & Headshop 1977
Nice find.
![Cool 8-)](https://www.defunkd.com/forum/images/smilies/icon_cool.gif)