Assuming when parked the wheels were straight ahead ( as pulling in the
driveway), and the keys were left in the switch (column unlocked) and the
Van rolled backwards, the wheels would of turned all the way to the stop,
either the left or right. The front end geometry is set up so the wheels
will return to center (facing forward) when driving forward. If not you
would have to fight the wheel at all times when driving, and the Van would
wander all over the road!

Think of a shopping cart, or any other type of wheeled car/truck or cart for
that matter that has "Casters" for from wheels. Notice that the pivot for
the wheel (caster) points down in front of the wheel. That point is where
the load is carried, so when you push the cart forward, it goes straight,
and the wheels follow. This is called (Positive King Pin Angle, or Positive
Caster) Older car/trucks with straight axle were tilted back in the same
manner. The pivot point (weight carrying point) was ahead of the center line
of the axle The front end of a newer car is more or less set up the same
way....... The Upper ball joint is behind the lower (Disclaimer: some older
Fo* ds) have negative caster. There powder steering handles the tire
"wander". A strut type front end has positive caster built into the design
of the car. Notice the strut leans back at the top.

Anyway the wheels were most likely held straight by the key being removed
and the column locking! Who knows for sure.

Cheers

Howard