I too have been looking for a modern manufacturer of flatbeds with the rounded corners and beaded side rails like the original one you pictured.
I would really like to have one made in aluminum, but so far no luck finding aluminum or steel.
Preferably I would find the components, primarily the side rails and corners, and assemble it all myself.

I'm curious what you find.

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-