I was given a number for what is supposed to be a oil temp sender which fits
into the sump plug socket of a wasserboxer, I've not been able to get one
but
the number is;
              VDO no. 323 801 0004 036
I was also told that the VW number for the same thing is;
               VW no N029 7012
However I have my doubts about this one. I got both numbers from VDO Kienzle
UK although they could'nt get one for me!

You are right to have your doubts. :-)  Not sure about the VDO one (I carry
VDO but not that #), but the VW number is for the stock drain plug, not a
sender.  The VDO sender I sell (# 323 888) is threaded correctly for a type
1 engine, so it replaces the drain plug on that, but requires drilling a new
hole on a Vanagon.  If there's one that directly replaces the drain plug on
a Vanagon, my VDO distributor doesn't know it, because I've asked.

- Ron Salmon
  The Bus Depot, Inc.
  www.busdepot.com
  (215) 234-VWVW