I am not sure if the 2 ton trucks were any different than the 1/2 ton trucks, but both my 52 GMC and 50 Chevy 1/2 tons had a maroon painted metal trim around them. Here is a picture of an un-restored 49 GMC showing the maroon trim and original door panel.
door panel As you can see in the picture this material matches the maroon seat fabric color and grain pattern.
seat fabric From my experience none of the reproduction panels from the vendors come close to matching both the color and grain. I used the seat fabric and applied it to ABS plastic to come up with something that is a pretty good match.
52 GMC door panel
