Wow guys! (Huge Grin!) But hang on, are we helping Barry here!
Still, its interesting, seems reading all, if the tonneau was optional (hooks installed or not), it wouldnt have been flat and had clips?

So does that mean, if Barry wants to go back to orig, he doesnt have to drill and find replacment hooks, he could just remove the clips (or keep them if he chooses too, its his ute, and tonneau is useful).
Maybe thats what happened, maybe it was orig with no tonneau, and then an aftermarket (flat) clip on tonneau was fitted? Its still part of the vehicles heritage if that happened of course.

I agree Innuendo, removing the service panels and having a good look (maybe with a torch and a mirror) should be pretty conclusive.