Go to your local junk yard/metal recycling center they usually keep trucks around for a bit until they have been picked to a skeleton. Well they do in my area. There also could be salvage yards near your that have alot of older medium duty truck. I personally know where about 100 c50/60/70 hoods are, they may not be completely solid but the whole hood is there may need some patching minor rust holes around the edges if your worried about that kinda thing. But I suggest searching google maps for junk yards/salvage yards/ metal recycling centers around you and go check them out and maybe even ask employees there if they know where any medium duty truck yards are for parts....
