Clifford - Did you check Maserati or Alfa rubber profiles against an original door seal? I found window channel felt, guides and the seal for mounting vent window glass to the frame at a Maserati parts organization.
http://www.maseratinet.com/ is one. The parts are organised by model, so look for models
that were produced in the 1960's. Ghibli is a good bet, and Mistral.
I used an Alfa parts company in Texas, who ordered the rubber from their supplier.
The actual rubber is manufactured in Italy by a specialist outfit. Once you know what you're looking for, it can be ordered. It can take a while, but this mystery manufacturer seems able to supply almost anything. Perhaps they were the original manufacturer, or have the tooling. Don't know....
Parts used by Frua for 428's were sourced mainly from Alfa and Maserati, or so it seems. I'm inclined to think that Mr Frua rummaged through existing parts to paste together the extremely low-volume 428, rather than design and manufacture discrete parts. I'd love to know where the windcreen, windscreen gasket and chrome finisher came from. It might be specific to the 428, but I'm inclined to think it's not.
As an example, Emmanuel bought a window lift for his car on Ebay. It was from a Maserati, and identical to the non-functioning one on his car.
