Sometimes the small jobs are the toughest. This one was many trips to dealers and over charge etc. For my 97 850 the answer was OSRAM 12V 1.5W bulbs (2) And I would have gotten then here, had I known:
http://www.12velectronics.com/servlet/the-18/Mercedes-VW-BMW-Audi/Detail

I still might have to because the first dealer gave me just one bulb without a socket and I fudged it up getting it into the old socket, but it still worked (for how long I don't know)

Also Haynes guide says replace whole circuit board, but that appears to be unnecessary

There is a thread on this subject here:
http://www.brickboard.com/AWD/index.htm?id=1021792&show_all=1

Hope this helps someone else