"Only if one is unconcerned about originality. I believe a 1968 280SL should have the black mirror, with the dull finish on the arm."
Waqas
Yes as Waqas says. I recently went through this. In my case the silvering of the mirror was showing its age. MB does not have the exact replacement mirror but they have a mirror, from a different model which uses the same head and a slightly different arm.
I took the head off the new and used it with my old arm. If you do this heat (gun) applied to the ball and socket will make removal and reassembly much easier.
Gus