If you are picky the rivets from cuda junction were a closer match to the original ones from a 1969 St. Louis built B-body, the ECS ones had a smaller outside Diameter on the head, not sure if all plants were the same. Might be hard to tell once it is installed but it was noticeable enough for me to order the cuda junction ones after I got the ones from ECS.
Not trying to bash ECS ether, nothing but good things to say about all their products.