First off, last year I had bought a 17" replacement unit for my rear window which came with a sturdy metal clip which wasn't needed at back. I bought another of these 17" units the other day and ended up with two of the clips, like so...
I took the clips & bent, filed and otherwise mangled 'til they looked something like this...
...and eventually after drilling and touch up paint, like this...
Then they screwed nicely into place and are ready for whatever unit I want to stick on there.
All told, about half an hour invested and they should last indefinitely.
