this is a seal that came in a master gasket set from the machinist when I picked everything up. There's no list or index for the gaskets so it a guessing game for the most part. Everything else is easily identifiable except this. I took it to Nissan Dealer & the old guy (my age) had to call a buddy to see what it is, best explanation is it goes between the head & block somewhere on the head gasket, perhaps by the center headbolt thats the longest one. I was told that if it didn't go back in it'd leak oil between the head & block, there wasn't one in the engine when I took it apart either.










as you can see its not very big, its maybe 8 or 9 mm across the top & 4 to 6 @ the hole.

who knows what this is & can I leave it out of does it need to go in?

Please let me know, Thanks - Evan