Rattling/Vibrating rear window

Just finished sound deadening my front doors and the whole back wall, and now all I can hear is the rear power sliding window rattling super loud. The bottom left of it seems loose and the rattling half stops when I put pressure on the bottom left. Is there a screw that could be loose or could I fix it by pushing some foam in the bottom?

 

Are sure put back panel on correctly? If it didn't rattle before you had it apart, and now does. I would look into that.

 

Sometimes the passenger seat belt clip will rattle against the plastic pillar in my truck if not secure. I've got a power sliding back window in my access cab but its very quiet.

 

I still haven’t put the back together, the back sliding window is definitely the issue and it did it before i even touched the back