>>9892058I don't have any Joytoy people, so I can't tell for sure. I've just tested on a Planet Green Valley girl with two choices: using the human lower torso or the gorgon one. I think Joytoy also has waist and mid torso joints, right? That's two chances to make it work.
Connectors are ball pegs around 4.5mm in diameter, give or take, I only measured it against a simple ruler.
(the figure is assembled and working in both cases; the long bar shown outside is an extra copy of the one that goes inside the tail, shown for reference)