Big Jim I think you are discibing the same thing. The slot is near the hub and goes aroound the entire disc and exposes the vents near the hub. My old rotors has a solid surface. I have never seen rotors with an area for venting.
Also I will be putting some anti-sieze on. I am painting the calipers this week end so that will be a good to to do that. When we did the rotors on my sons 95 we had to cut them off they were so rusted. We put anti-sieze on them.
Rich S.
