Yep, I tried to find a socket that would fit, everywhere, I ended up buying one from Pedulla. BUT a buddy of mine said, the shape and size of the truss rod, looks like a DRUM KEY would fit it, but the outer diameter of drum key is too big, I spent all of a Saturday, going to all hardware stores, hoody stores, etc, trying to find a tool, that would fit on the truss rod.
I like saving money, but getting a wrench from Pedulla, to be safe, makes sense too.