At the mercedes made in 1983, 300sd, which fuse is for the clock?Which numbers are on the fuse itself, or which position is the fuse among the other fuses in the row?
If your clock has stopped working in your W126, it is most likely not a fuse problem but instead the clock is broken. Below is a link on a step by step DIY guide on how to fix the clock. Edit: Sorry I couldn't be of help but I could tell if I was back home and took a look under my hood and the fuse box. I am currently on business in Korea and won't be back home until Oct. 3rd. I believe the fuse box label tells you which fuse it is, and fuse is used for other electrical components too. Below I found some more links dealing with the fuses in a W126. Take a look at the w126.pp.ru/fuse.htm link towards the bottom of the page (fuse #13).
Simply look at the fuse box and it will tell you what fuse and the power of the fuse to use.