Paul
Our local midwest yards still have 1968-73 GM vehicles holding these.
I usually pick them up off the ground,if the body panels themselves aren't still holding them.
I just clean em up,then hit them with a matching hobby color.
I've even found a foam rubber that is perfect gasket material.
The pair on the far left is done.The others are as found.
I can gladly spare you a couple if you still need them.
Rick