Mystery Part -'94 PWR Steering pump replace

Replacing my Pwr Steering pump and didn't see where this part came from when taking the pump out. Is it the union seat for the Air control valve or does it go with the main ATF fluid banjo bolt? On inspection, it fits on both. Watched a half dozen early 90's toyota pwr steer vids and this part is never shown or mentioned. Before I leave it on the workbench and bolt everything back together, does anyone have a clue?

 

Best exploded diagram I could find - looks like it may go in the Air control unit. Still not sure but I'll give it a shot.

 

Following.

 

Found another PS pump diagram and I think the verdict is in. That little critter (union seat) is going in the air control valve when I put it back together this weekend.