I have just bought a late Devon roof, and the part you are missing is a fabricated square tube that screws to the roof of the van and the pop roof clips to it. Here is a phot of the front one, I am missing the rear but can make something to match. Once fitted, the roof lining trims over it like Snottys photo, perhaps it has been removed or never fitted
Happy to send you some better photos, but I’m not changing mine over for a while yet.... I’m sure we removed the other one from the donor van but just can’t find it.......if you made something that doesn’t look too rough, you could screw it over the trim?
Sorry, I didn’t check back on here earlier. I’ll get some photos, and post them up over the next day or so.
That is very helpful, thanks ever so much! I’ll let you know how it goes (Although it might be a little while until I get round to it)!