My 08D 69 was red oxide. That's what I tried to mimic when I built it. Mine came out a little darker, but I liked it. In the below pics, you can see the back seat braces are original and the inner fenders and floor I replaced are what I painted.
I toyed around with the idea that it could have been grey primer that had HO misted on it from painting the body, but I decided that wasn't the case after looking at certain parts that weren't as faded as others. Like the back seat hump.
My original hump laying on the new floor.