I'm trying to sell the Audio 20 from my 2006 W203. A prospective purchaser wants to buy it to replace an Audio 10 in his 2003 model. Am I right in thinking:

1. It won't fit; and
2. It's not compatible because the earlier model uses d2B fibre optics?

If there is no phone or CD changer involved, does the different fibre optic still render them incompatible?

Overarching question - does this Audio 20 fit and work in any model other than the post-facelift W203?