BJ - I will need to check but I am pretty sure that the dog guard that Landie supplied and fitted in Mrs N17TVR's Freeloader is mounted in brackets in the floor, but has a 'screw tight' mounting to the ceiling.
I have since found this out, and the one I am biiding on on ebay comes with the mounts - so hopefully I should be OK, if not you can buy the kit from LR for about £30...