If you have a 1977 or earlier it's easy - http://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_BRKprf_pg11.htm#item10
Of course you and I don't, so I would like to have an answer also!
"I have no idols.. I admire work, dedication and competence." Aryton Senna
PCA National DE Instructor
2014 Porsche Boxster / 2009 Porsche Cayman S / 1997 Spec Boxster Race car