TF rear crash cans.

One further thought. Don’t bother with the reversing alarm with displays. A bogo bleep bleep is all you really need, looking at a display means your not looking at what you are doing. A bogo will tuck nicely behind the boot hasp strut & you can pick up power from the reversing lights. Use a Jack plug & socket to allow you to unplug when the light contact tray has to be removed.
The bleep bleep sounder is tucked in the carpet folds near the seatbelt anchor.
M

Yes do it that way, I wish that I'd done that before attempting to undo the torx bolts to the cans.

I cut the bolts holding the cans to the bumper releasing them, then decided that they were not reusable because the bracket had twisted too much to twist back without it breaking off.

Sometimes sacrificing parts to aid dismantling is the best way.
It’s not a way that sits well with someone with an old fashioned small “c” conservative outlook, especially if the replacement part looks over priced for its construction.
However the time expended in repairing a mangled device could be more profitably used elsewhere.
I frequently wonder why I don’t follow my own advice.
M

Sometimes it is better to be ruthless and sacrifice a part than waste time money and effort trying to reuse it. Which is what I was getting at when I explored the idea of cutting through the can, it may have been the best way to get the bumper off if the can had already been mangled in the efforts to remove it.
But it also pays to check on the cost and availability of the part in question before you go and get all medieval on it's sad and sorry arse! 

I'm eyeing up some S/H replacements up on the bay for possible purchase. Doing a lot of underside surface rust removal at the moment then painting the areas.