Lance has no drawings for older frames. Anybody saved some?

Thanks. I got some view on the construction after removal of propane box.
Somebody was there before as bottom of camper has added siding with different tone.
The main board under the slider is 3/4 x 2.5 with 3/4 x 1.5 added to make angle channel.
No wonder whole thing had to sag and staple holding it at joints simple broke.
There is only so much siding can hold together.
At this point I will try to buy 2x2 aluminium channel, that HD stocks and add it under siding.