Could they be the rib sided ones Austrains did?
I can't see shots inside the wagon though, but others in the know, may know.
I reckon this web archive is great for looking up what manufacturers have made over the years.
I have seen another VR modellers website where almost all the HO scale models produced of wagons and locos have been listed. I can't remember it off hand but a search of VR modelling may yield something.