Try Steve Nervig's index which is a heck of a lot better than MB's interface for finding the appropriate section of the FSM -

http://web.mac.com/dakota/Mercedes/Indexes.html

Here's some information on the index -

http://www.benzworld.org/forums/w126-s-se-sec-sel-sd/1395058-service-manual-index.html

Sixto
87 300D