Ford 1997 Aerostar Manual page 217

When one of the back wheels is off the ground,
the transmission alone will not prevent the
vehicle from moving or slipping off the jack,
even if the vehicle is in P (Park). To prevent the
vehicle from moving when you change a tire, be
sure the parking brake is set, then block the
wheel (both directions) that is diagonally
opposite (other side and end of the vehicle) to
the tire being changed.
If the vehicle slips off the jack, you or
someone else could be seriously injured.
2. Get out the spare tire and jack.
The jack, jack handle and lug nut wrench are
stowed separately on the left hand wheelhouse
inner panel on standard length models. And in
the right rear storage compartment on extended
length models.
Jack stowage
RWARNING
217