Its the trim around my back window the grey trim that the weatherstrpping goes onto.Mine somehow got broke and its lettin water in i think its just clips holding the plastic on.

https://www.f150online.com/forums/me...not-bolted.jpg

 

If it's leaking it isnt the plastic part... You need to do that whole how-to (where you got that photo) and re-seal the window frame.

 

I had the same problem with my back window too (before I did the how-to fix mentioned above) and when I tried to just get the trim/weather stripping from the dealer...they said it only comes as a full back window assembly...not in parts. At least, that's what the dealer told me here in Cali. If you just need the grey trim, I suggest doing some searching at junk yards and then put it all together using that how-to. Good luck.