intake/exhaust mounting, what am I missing?

Hi Dne
Yes, I know this subtility for the old (with 3 conical washers) and the newer manifold (with only one)., but I don't know what these washers look like.
Now on your picture I see the conical washer. Thank you.
But I think that you don't use the correct nut. There, I think that you must use a classical nut, not this creneled one which goes to the far outer left and right studs and the brass washers. But I can be wrong....