Richard,

If you decide it's worn upper control arm bushings (most likely)
here's a how-to on the subject:
http://www.vanagonwiki.net/index.php/Upper_Control_Arm_Bushings
--
John Meeks
'91 Multivan, '85 GL bits
Northern Michigan
KC8ZFN
Vanagon Rescue Squad
http://www.vanagonauts.com/Vanagon_Rescue_Squad74.htm

On Thu, Mar 6, 2008 at 1:17 PM, Richards, Andrew
<Andrew.Richards@nike.com> wrote:
> My van's front end seems to knock (sometimes squeak) a lot when on
>  rougher to rough roads.  My shocks are new, as are the upper ball
>  joints.  Lower ball joints are intact.  Everything else is most likely
>  original (160K).  What are some possible sources?  Loose steering rack?
>  My mechanic has told me more than once, "everything seems tight and
>  looking good under there"....
>