What is this piece?

That is a hold down spring/clamp however you want to call it for the orange steering coupler seal. In the perspective of your picture, you would push it to the right as far as it will go so that the flat part sits against the face, it is meant to hold down the seal so that it doesn't come loose.
You can tell if its power or manual steering by looking at the box to the right of what is not pictured.