Originally Posted by repechage

Yes, that box looks like for a rear mechanism.
those came in various ways, some with the mounting claw, and even bottom bracket cable guide, cable and stainless cable housing with end fittings.
the Front mech box was smaller and if it has the black arm, would have been in a fold flat blue box.
I don’t have many campagnolo boxes. I was cleaning up the bike room and found a second box of NOS SL pedals. Nice surprise.