Need some help finding a packing nut for an older sillcock in our laundry room.

The nut is unique in that it has two sets of internal female threads, one for the outside of the sillcock body, and another for the larger male threads on the valve stem. It sort of looks like a flare nut, with the female threads for the valve stem in the flared portion.

Technically speaking, I suppose it isn't actually a packing nut because there isn't any need for packing material under the nut; instead there is an o-ring in the middle of the valve stem that keeps water from leaking out the top of the nut. (This is how I cracked it--trying to put packing string under there when it wasn't suppossed to be there...)

Anyways, I've looked at all the sillcocks/valves at Lowe's/Home Depot and all of them have them have the female threads for the valve stem inside the sillcock body instead of the nut. I'm guessing mine is just an older style that maybe isn't used anymore. Does anyone know where I might find a nut like this or a sillcock with this kind of nut? Does this even make sense? Thanks in advance.