using the v8 landrover mounts

[jps]

picked up my landrover mounts today. first thing that struck me was the threaded sections on either side aren't very long, 15mm at a guess.

my plates on the chassis are 6mm, which doesn't leave much space for a nyloc on the u underside. what has everyone else done to secure these? tap a thread into the plate? weld a nut on the underside? or do nylocs fit?