Have a look at the picture below. It states for the 230SL "Spiegelbildlich zur Fahrertür", which translates to "Mirror image of driver's door". Essentially, the book says the mirrors are placed in the exact same locations on both doors. I guess you could mount it further forward if you wanted to, but I guess it depends on how finicky you are about originality. However, bear in mind that the mirror opposite the drivers side is to have a convex glass to allow viewing from a distance. The part number for the left side mirror is 113-810-06-16, and the right side is 113-810-05-16.