In replacing the headlight switch in my '90 Westfalia I've encountered a
curiosity, maybe even a mystery for the list wizards.
The VW part number for the headlight switch is 251 941 531 'X', the X
being one of several letters.  ETKA says M for all but the late 90-91,
then T. According to the info and pictures on vanagain.com there is an
additional pin on the T version.  But when I called the local VW dealer,
they said L.  The switch that came out of my van is a K!  And here is
the best part of the mystery.  I tried a switch that has a B designation
and it seems to work perfect, all light work!  And the B switch is
missing several pins that are on the K that came out!  But even with the
missing pins, it works perfect!
I've taken pictures, and stolen a couple pictures from Ken at Vanagain,
showing the socket and the various switches.  You can see them here if
interested:   http://tinyurl.com/69qol
If anyone can explain to me why the B model switch with the missing pins
works in place of the K model it replaced I'd be very interested.
BTW, it appears that the only available replacement for me, with all the
pins, will be the M model which I will be ordering.  And then I'll get
around to installing the relay kit that has been sitting under the back
seat for a year and not fry another switch.