Where does this piece go

[Matts440]

I've tried searching for window pieces to see where this goes but no success. Is it part of the window assembly or a interior panel part?
Thanks

 

[cudacrazy67]

That's the sill plate extension. It goes between the bottom of the backseat and the interior panel.

 

[Matts440]

Oh okay thanks, no wonder I couldn't find it under windows lol.