I have a 1993 mercedes 400e and the #3 fuse keep blowing. What is the correct fuse for that slot

First thing u need to find out is what the fuse runs and check to see if there is a reason for the fuse to blow it could be a short in your wiring and if you put the wrong fuse in its place you could burn up your wiring but the cover for your fuse block should have the correct fuse on it if not check your owners manueland if you dont have one you can visit your local auto zone and look in there chiltons manuel to find what your looking for