Stock Valve Cover Identification

I'm cleaning house and have 4 sets of stock valve covers 3 big block and one small block, but can't remember what year they were from. I just finished running these through the hot tank and they cleaned up nice. I will eventually post pics and sell but I want to advertise the correct year range.

Is there a web site available with photos for identification?

Thanks, Doug

This may help.

http://www.1970gtxregistry.com/1967...0valve%20cover%20reference%20photos.html

Perfect! Thank you!
I have 2 sets of 71 and one set of 70.