Need exterior trim piece

you might try here
https://www.icondirect.com/

Try this outfit: https://www.all-rite.com/

Most moldings / trim are fairly generic, in that most mfgs don't make their own trim pieces.

Try Bontragers RV Surplus who are located near the RV capital of the world. They are one of the largest RV surplus outfits around and if they don't have what you need nobody does! I have been there numerous times and each time am amazed at the stuff they have. :E . Scroll down near the bottom of the page I linked above to see pictures of just a bit of the things they have available.
Barney

Try this clicky - they make a lot of moldings, trim and seals for the RV industry.

Thanks for the suggestions.
No source located.
Have replaced both sides with sheet metal covered with thin aluminum diamond plate.