Page 5 of this Samba thread shows a photo of a truncated tunnel on a Westy ceiling, but it might be as easily applied to a sunroof van:� 

http://www.thesamba.com/vw/forum/viewtopic.php?t=424773&start=80

Good luck!

Stephen

--- On Sat, 5/14/11, Steve Drier. <Vanvw1@AOL.COM> wrote:

From: Steve Drier. <Vanvw1@AOL.COM>
Subject: Sunroof - A/C
To: vanagon@GERRY.VANAGON.COM
Date: Saturday, May 14, 2011, 11:37 PM

I want to install a sunroof in my 91 Carat.

In that connection I would like to terminate the A/C tunnel and� housing
above the back bench seat/bed leaving the area over the front seats� for the
sunroof. I live in the pacific nw so A/C is not a must and I still will� have
enough flow to cool the van down.

My question is has anybody done or seen this type of modification.

Steve