There are so many things bolted to the frame I think it would be a mistake to fill any of them, and no real benefit in my mind.
If you are dead set on filling them about all you can do is assemble your truck, then you can see the unused ones.
Perhaps looking at a similar truck would answer some questions, but there is a good chance that that truck has something missing, or something non factory, and you still don't have all the answers for your truck.
Grigg
