Thanks for the responses.  I guess there is no adjustability in the vanagon,
as built by the factory.  So I'll have to figure out the best way to adjust
on my own..Shims were suggested.  I'll have to get under and look at
everything more closely.
   In my experience, it takes very little ride height adjustment to greatly
affect the amount of traction in a vehicle.  My racecar was very sensitive
to as little as a few millimeters of change, with huge differences in lap
times coming when the suspension was 'off'..  A few millimeters would cause
the corner balance to be way off...which in turn affected the available
drive significantly.  If you have an "open" differential, as my van does (no
limited slip) if you have say, 100 lbs less load on one rear wheel, that one
will spin very easily in low traction situations.  100 lbs less load could
be as little as a few millimeters of ride height difference...An inch total
difference, corner to corner, could actually cause the light wheels to leave
the ground at times...not good for impulsion..
  Now, in most situations, it's probably not that important.  But I live on
a hill and it sometimes snows.  I need all the drive I can get to avoid
having to chain up to get home..I also drive in sand and mud and on
rain-slick roads.  More traction is good...If a bit of adjusting can help,
it will be worth it..I've also been looking at locking diffs, for when I get
stuck..And at installing a limited slip...but cost is a factor there..
  anyhow, thanks for the responses..
  Don Hanson