What he actually needs is a dealer data book. I can't find mine at the moment ... (Dan ... it didn't end up in that package you received, did it? Maroon cover, spiral bound?).
I need the book to confirm, but its my understanding that the beds from the AD era had rounded sides. That does look like a factory-built bed, not a shop built one, though. It could also be that the truck was sold as a C&C and the first owner put an after market bed on it. Or ... the first bed has been replaced with this bed. At any rate, that bed is so nice looking (love the round corners and the metal stake ends) that it looks original.
The fenders probably were added by whoever fabricated the trailer hitch. They're not stock.
Have I mentioned yet that it is a very good looking truck??
And surprising that such a good looking 3800 was lurking within the area of the Old Dominion Stovebolt Society ... Apparently, the ODSS radar is working as well as it used to ...
