I went up the road to where I got the 6 seater from, to show my friend a photo of what the truck looked like originally. He said I better come for a walk up the yard and have a look at the other bits that he had found in the last few days and see if they were part of the truck.
I now have the original roof and the front door posts. It appears my friend's Dad had started to convert the 6 seater to a F15 or wreck it, not sure which.
Here is a photo of the door posts, a photo of the interior of the cab and one of the very faded tac sign.