Hi there - does anyone know what this part is?

Finishing up a rebuild on my '99 Outback EJ25 DOHC. And Ive got this one part I don't know where it goes. Cant find it anywhere online, went in to Subaru and they don't even know.

The number engraved on it is: 537046 2600

Below are links to photos of it.

Thanks in advance

https://i.postimg.cc/bJwqM0KM/92-FA6...EA-1-105-c.jpg

https://i.postimg.cc/d04Y8kL9/F78405...F2-1-105-c.jpg

https://i.postimg.cc/CLPrHGN5/293-FD...69-1-105-c.jpg