Hi Nigel
My LAAT truck body is all steel, It Appears to be a collection of pre-formed sections, Side Panels and locker boxes all being interlocked/ spot welded together, A bit like a car Body shell. The main structure has steel channel cross members at regular intervals welded to the 2 main longitudinals that sit onto the top of the chassis.
To re fabricate a new body would be an extremley long drawn out process.
On the plus side most panels are FLAT, All bends are at 90 Degrees.
You would need access to
Covered work area to place old Truck body on the floor so that you can make easy cross checks as you proceed.
space to build new one alongside. maybe on a DUMMY chassis frame made from two RSJ beams set level to ensure that the new body is level and true. Better than the truck chassis as there are no wheels axles drive train or petrol pipes to avoid. Lots of Commercial bodies are built on the floor so to speak
A folding press break that can handle 2 mm sheet,
A Guillotine to make cutting sheet square with least waste.
Good welding skills I would imagine would be a great help.
IM me if you need any pictures,
The body on my LAAT was built by THE FROST AND WOOD CO LTD.