I have a question - doesn't the jack base, upside down, fit through the center hole of the wheel and act as a spacer/washer for the hold-down wing nut? Just curious, it's been years since I've had a car with that set-up, but IIRC that's how it went together on those, though I may be thinking of Chrysler products.
Now that I remember you are correct, yes, the base of the jack does fit through but the problem I found was that since the wheel is forced to rest on the jack it moves and makes noise when going over bumps so I took it out.