Scott seems on target on the two styles.   I bought what is a half and half on ebay only to find the pane was smaller than the one in my Westy.
I was able to replace the pane only but it was a pain.   By removing everything from the replacement window you can pop the glass only into place.   Then you can slide the slider that you removed from the replacement window under the window and your back in business.   In my case I am still shy about 6 inches of window.   I am thinking plexiglass to bridge the gap.   Thanks Scott, from the better continent of the world.
              Gary
Date:    Wed, 22 Dec 2010 19:56:33 -0800
From:    Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Subject: Re: sliding window 87 westy

one style is for Westy's and the other is for 7 passenger vans.
And there is minor variation from early to late ones 'I think.'

in any case ....I have one or two of those windows for sale.

Scott
www.turbovans.com
----- Original Message -----
From: "gary hradek" <hradek@YAHOO.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Wednesday, December 22, 2010 7:32 PM
Subject: sliding window 87 westy

> What is the deal on these windows.   Some are half and half and others are
> one third and two thirds.   What went where if you need to replace a
> broken pane?   thanks, gary