I replaced the vapor barrier on my 1990 Westfalia about 3 yrs. ago and 
the pieces (2 per door) were available at the dealership but were very 
pricey-about $70.00 to do both doors at my dealership cost. The plastic 
is formed to fit the contour of the inside of the door and has gooey 
adhesive around the edges to give it a fairly watertight seal. On my 
vehicle there was one piece that was formed, shaped plastic film that 
went on the bottom 2/3 and then a gray thin foam piece for the top. The 
pieces do fit perfectly and if you need to get to something later on 
inside the seal you can peal back the plastic and then reseal it to the 
gooey (kind of like the stuff a lot of mechanics called "dum dum") 
adhesive. I also attempted to fix the waviness in my door panels from 
the old leaking seals  by wetting them down with a spray bottle then 
putting a flat board with lots of bricks on top of it while it dried. 
Seemed to get it closer to flat for a while then the bends and curves 
came back. I am sure others will chime in and suggest other non OEM 
seals that work perfectly fine and certainly function over form as it 
is hidden. I just didn't trust anything to not get caught in the window 
or lock mechanism along with it sealing well and not coming apart with 
temperature changes. YMMV. Oh and what have I done for my van lately? 
Replaced the upper control arm bushings that failed after only 10,000 
miles (Meyle). So I went back to the OEM-Lemfoerder that lasted 20 
years and over 275,000 miles and also installed another set of Gowesty 
progressive springs to go with the low mileage Bilstein HD shocks and 
struts. Rides like a dream and when I went to get it re-inspected (it 
failed Va. state safety inspection for a collapsed bushing) the 
freaking headlights quit working. I have the relays upgrade and suspect 
something there was amiss. Okay, the real story is that the Westy 
ceased to be my daily driver as of about mid march after 12 years of 
grateful service. Now I get into a Honda Civic every morning since I 
have to drive about 1000 mi./wk. for my new sales job. She is jealous 
and acting out. Must show her more regular TLC or suffer the 
consequences! Hell hath no fury like a Vanagon scorned! Happy Fryeday 
all. Going to imbibe mass quantities of forget your worries beverage 
now.

David Clarkson
1990 Westfalia (jealous and persnickety)