BP 408 Oil Leak

The later small blocks the filter adapter surfaces are different. Put a small straight edge across the inner and outer gasket surfaces. You'll find that one is even and the other is offset. When I built my R3 block I had to get one for a new magnum. But the crate motor we did I used the early style. So to answer your question they are different. You need to set your adapter on a table and see if yours is offset or not. Then check the block. I fought the same thing.