The impossible air conditioning connection

[davepl]

So I'm hooking back up all of the AC during reassembly of my restoration, and I've run into something I just can't figure out.

On the line in the picture below there is no tubing nut. I've followed the line up and down and it's just not there. Yet I don't know how it would have ever come off, because the flare is still on the end of the pipe.

In the assembly manual it seems to show the pipe without a tube nut, but that's hardly authoritative.

Could someone with AC (ideally a big block, but probably doesn't matter) check theirs and see how it's connected?

Many thanks for any help! The second photo is just a quick snap of where I'm at. It's still all the original lines and so on (which hopefully do not leak) plus a lot of scuffing, polishing, scotchbrite, and so on.