Reviving the thread 20 years later... Has anyone actually done a Seicento/Cinquecento mirror swap? I'd like to put a Cinquecento mirror on my Seicento. The real problem seems to be the corrugated rubber boot, which is cylindrical on the Cinq but has a squarer profile on the Sei. Is it solvable? Can you stretch the Cinq boot onto the Sei backing plate clips?
All I need is a custom 3D printed rubber part, lol.
EDIT: I took the plunge and bought a brand-new Cinquecento mirror for all of £10. It fits! The outer baseplate isn't identical to my Sei's (1999), but it's near as dammit. Instead of one edge overlapping the window rubber, it sits under the rubber. Otherwise, all matching. Fab.