Yall are going to think I am crazy........and shut up.......but I have never in my life seen the recesses in a small block main cap for those wings to go like that. Never. All of them I have ever seen and or put together like this were flat on that surface and had a standard rear main seal with no wings. This is new to me. .......and I've torn apart and assembled a lot of small blocks. I wouldn't like this. To me it's one more place to have a leak or some other problem.