Hi lads, the brackets in the image that Hodge posted are from Rhino. We do make L brackets that are designed to sandwich between the rack mount and the rack itself (this can be done with Rhino mounts as well). There are a range of options depending on vehicle and rack style, so I won't post a part number. Your best bet is to drop in to an ARB store/stockist and get sized up.
Any dramas, give us a shout.
Cheers
David