I'd say they are not factory as the assembly plant wouldn't have done this. They could be original (as in original from delivery) and be dealer fitted or dealer organised. The fact they have no other paint is not surprising as they would have been bought new. The words on my site were from a source that had told me that some GTS guards were fitted to Sandmans after GTS finished so that would be after around 3/79. None have yet turned up so I doubt it was done. The assembly plant would be very unlikly to have done it, they didn't even fit basic things like mudflaps unless they were part of a vehicle package. Nothing is impossible though!