By your description, I'm not sure exactly what you mean, but I thinks this is the one...?
The official part number was A9748033-## in the Blue Triumph Accessories & Clothing Range 2004 Catalog, Page 17.
This custom paint kit was available for the T100 and Thrux with confused different part numbers due to mounting and moving the turn signals down.
On the Thrux it matched the Tank and Seat Cowl, with gray front and rear fenders. It was all screwed up for my T100 in a custom 1/2 year offering. We had to call the factory and getting the little mounting things right took 4 months. Mel-of-a-hess it was getting the right fitment kit IE: Thrux Bracket and Screw Mounts vs. Rivit kit Mount for normal Bonneville/T100. But I got the Fly Screen. I have both mounts and currently have the Thrux Mount installed, even though the Bonnie/T100 Mount was better, though I decided to use my own thumb Screw Mount with their bracket, rather then riviting for the Bonnie/T100. The gold Bonneville Decal across the fly is my own I added - if you can see it.
You would probably have better luck getting a generic Decal and placing it on the Black Fly Screen these days.
Good luck...
