I never could figure out what it is that we are trying to seal out or seal in. I had such a fit with the aftermarket ones that I threw the seals and clips over the fence and 2 or 3 houses over.
I haven't noticed anything leaking in or out for over ten years.
The only clip that matters is the one that holds the bezel to the bucket. I ended up using epoxy to hold those in place then bent them into the proper position to hold the bezel to the bucket.