http://www.mar-k.com/
Should sell most any length you need.
I expect they have a shape that's very close if not exact, certainly something functional.

http://www.mar-k.com/CustomForms/BedStrip_AngleStrip.pdf

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-