below are some pictures showing FAT chassis. The first is from Service Publications disc of factory photos the second and third are labled as CGT but shows how they came from the factory. I am not sure where I got the last 2 photos from.
I'd like to suggest that as this was an evaluation model bought here for testing that you restore it as supplied from the factory or with a truck cab rather then try and put a FAT body on it.

This is just my 5 cents worth
__________________
Cheers
Cliff Hutchings
aka MrRoo S.I.R.
"and on the 8th day he made trucks so that man, made on the 7th day, had shelter when woman threw him out for the night"
MrRoo says "TRUCKS ROOLE"