Used ali shim on mine drilled a hole all the way from the bottom to the top then welded a nut to the top of the chassis and put a long bolt all they way though.
I found me left side was wonky so drilled out the hole on the bumper till it would sit straight.
The ali shims where added to stop the wobbling.
To stop it twisting I put a hole in the side of the chassis - no hole in the tube behind. I tapped the and put a bolt in which stops it turning (one for each side).
So one bolt top to bottom to stop it pulling falling out then one in the side to steady it.
It is a bit of pain getting the side bolts in with the tub on but it made all the difference.
I hope that helps
