How thick is truck bed steel? I'm trying to figure out how to remove just the flat material. Can I find a tool to just cut it out and leave the cross braces? The shell is solid.

 

My guess is about 16 guage. I removed mine and left the cross braces, but it is a job with all of the spot welds. After I got an open space cut out, I used a chisel to go after all the welds on the cross braces and then cleaned them up with a grinder. I had to come up with a new cross brace for the front of the box, so I used a signpost. Here's a few pics of what I did. Taking the box off saves a lot of bending over. After it was all welded up I used white oak as the bed with just some Water sealer on it. It works well for me but not for everyone.

 

Thanks. I would not have tried that. It sure turned out good. Mine is not quite as bad as yours was.