Utiline Box Support Questions

[67step100]

I have a '67 D100. I am removing the wood floor from the box so I can sand and stain the wood. It was never done by a PO but the wood, white oak, is still in excellent condition. My questions concern the cross member supports and the the support of the box itself.

The first picture shows the 4 cross members under the box. Only cross members 1 and 3 are secured in place while numbers 2 and 4 move freely once I removed the wood boards. Cross member 3 has those rubber bumpers under them. Should these also be under #2, but there are no holes to secure a rubber bumper to the cross member? Cross member 4 is shorter than the others (see second picture) and just sits on the frame rails apparently and is held in place by the bolts holding the wood planks. Is this correct?

When I removed the outside board on the right side, the back end of the box dropped about an inch. I raised it temporarily by putting some wood blocks between the back end of the box and the frame rail (see second picture). Does this make sense that the box would drop? It doesn't seem to be attached to anything, except the 2 large carriage bolts on either side at the back. Is that right? I left the outer most left board in place for the moment (see first pic) so the box would remain at its correct height. The two large carriage bolts passed through wood blocks, maybe 3/4" thick, when I removed them.

Seems kind of a hokey way of securing a box to a truck frame. Is what you see in the pics and what I am explaining sound correct? I can provide additional pics if needed. I'm sure I'll have more questions once I get some replys. Thanks for the assist.

[67step100]

Getting no response so maybe my questions aren't clear. I was able to find out a bit more when I used the search word "wood" which was a help. However still do not know about cross member 2 in my first post. Here is a pic of it in place before I removed the boards. It was screwed to the boards but the cross member was not sitting on anything, like it was on cross member 3. The next picture shows cross member 2 from the other side. There is a hole in the cross member and a support arm on the frame rail so I assume there should be something there? Maybe another rubber mount (next picture of cross member 3)? If so how thick?

The last 2 pics are I assume the front supports. There is a wood block, rubber spacer and a couple of fender washers. The 4" carriage bolts pass through all of these. No questions, just thought I would post a pic as I haven't seen any others posted.

[DukePW]

I have a short box Ute bed I am not sure what you have. I have 6 carrage bolts that hold down the bed. They each go through the wood, through a cross member, and to the frame.
On my shorty, the #2 cross member as you call it has a rubber bumper between the frame and the cross member. A carrage bolt also goes through it and goes through the 'L' bracket on the frame that you show on another pic.
That might answer some of your questions?