I noticed on the parts list that different parts of the sunroof were vin specific. Does anyone know if the complete units from 2002 will work in 2003? Are they interchangeable?

I have 2003 s type m51410

 

Yes. i have googled on the net and find out some auto parts sites in which they are mentioned that the sun roof parts for s-type, is almost same for 2000-2006 all engine models and submodels. so repeat the same and read the fitment note for the parts you need. you'll get the better idea.