So if a part like this RCM as listed as being correct for Mercedes Benz SLK 320, 2001 - 2004, convertible, naturally aspirated, it would likely be correct for the Crossfire? There is one on ebay right now under P/N 170540305, which they say is right for the above vehicles, but they have no way of cross referencing it. Is this the "accepted" P/N for a Crossfire RCM? So how would any dealers or parts outfits know any of this? I guess I'm trying to sort through what seems like an "impossible" parts supply situation for a Crossfire.