For those who are installing new springs, you may want
to consider using leveling shims for the westy list to
the left.  The shims go abobe the spring, and above the
spring rubber...actually between the spring rubber and
the vehicle body.  Rough dimensions are as follows:

The front shim is like a big washer with a big hole in
the middle.  Outside diameter: 5 3/8"  Then cut a 3
1/2" hole in the
middle.  You end up with a big washer.  I used 1/8" on
the left front with nothing on the right side.  You can
safely
go 1'4" up front.  If you put 1/4" on the left front,
I would put 1/8" on the right front.  Otherwise, just
1/8" on left front.  Post 1990 vans sit a little lower
up front due to the cast control arm.  A 1/8" spacer
will give you close to 1/4" additional height, so be
careful not to go too high.

Rears:
Outside diameter 6 1/4", and then a 2" hole in the
middle.  I would go 1/4 - 3/8" on the left rear.  I
have 3/8" right now and it is a little high in the rear
now relative to the front.

Hard plastic works fine.  I had shims in long before i
got springs made.  One set i made from a plastic
recycling bin and had in for two years.  There were no
signs of wear or flattening when i removed them.

Steve