What material are your crossmembers made of? I have seen both wood and metal. My Chevy factory sales literature shows metal crossmembers. If metal, then carriage bolts would be appropriate. If wood, then you could use carriage bolts, nails or deck screws. My Diamond T and Chevy COE beds are both the same make (LoadKing)and have wood crossmembers. The original bed planks on my Diamond T are held with nails. When I restored the Chevy COE, I went modern and used ceramic coated deck screws with torx head. I was not confident with my hammering skills as the crossmembers are made of popular, so I abandoned the stock look. Both beds are 8 ft. wide.
Kent
