A bent frame is always possible. It may be that there has been some collision damage that has been repaired. If the box doesn't show any signs of repair work, then maybe it was replaced as a unit and the frame or mounts never completely dealt with?
If you look under the bad, you can get a look at some of the mounting points. The box mounts to some rails that run perpendicular to the frame. They are strong, but made from thinner metal. You may be able to see signs of deformity on those if you have a look down their length with a light. You can see at lest two of them in the wheel well area.
Another possibility is that the frame or box mount was bent by something like the truck being overloaded. A lot of folks tend to think their half ton can carry anything that fits in the box. The most common thing I see is a half ton carrying a box full of soil, gravel, bricks, etc.. things that are going to be well over capacity for a truck of this size.
Not sure if any of this helps, but may give you a couple of things to look at.
If you look under the bad, you can get a look at some of the mounting points. The box mounts to some rails that run perpendicular to the frame. They are strong, but made from thinner metal. You may be able to see signs of deformity on those if you have a look down their length with a light. You can see at lest two of them in the wheel well area.
Another possibility is that the frame or box mount was bent by something like the truck being overloaded. A lot of folks tend to think their half ton can carry anything that fits in the box. The most common thing I see is a half ton carrying a box full of soil, gravel, bricks, etc.. things that are going to be well over capacity for a truck of this size.
Not sure if any of this helps, but may give you a couple of things to look at.
