positioning two parts on their centerline

I have a simple beam I constructed with Frame Generator. I have modeled up a little lug that I want to sit flush on the center line of the beam.

How do i do this?

I have read countless tutorials, and I understand how to mate the two parts. Once mated though, how do i position the lug to where I want it to be (in this case on the center line)

Thanks!

Once mated though, how do i position the lug to where I want it to be (in this case on the center line)

Mate constraint. That simple.

Zip and attach your assembly here.

Apologies for the state of the model, I may have gotten a bit angry and went haywire on it in frustration. But essentially I want that lug to sit flush and in the center of the top of the beam.

VentSpreaderBar.zip

Thanks in advance.