Squarestream upper moulding cap

[bajadosmil]

I'm looking for the cover cap or moulding cover that snaps over the upper aluminum moulding. This moulding runs down both sides of the roof and across the joints at the roof end caps The dim is 3/4" aprox and the local airsteream dealer has a blank look on there face when I inquired, tried to sell me a window hard plastic part ? This stuff radius's around the corners (yes these square ones have a few round places too) so what ever was there originally was flexible

Any resources ?

Thanks, Tony