I believe these go somewhere in the door or window assembly but I can't figure them out. I've been looking at pictures and videos and searching restoration parts suppliers for days and haven't seen them anywhere.
Those are the pads that the windows slide up on. It's been a long time since I was inside a foxbody door. Somwhere in the middle of the door towards the top there should be a bracket those screw into that hold them against the glass.
It's been at least 20 years since I have been inside of a Fox door. Hopefully someone more familiar will chime in soon. If they don't, look at the glass itself. Odds are that pad left some sort of trace track on it. They notoriously get full of dirt and mark the glass.
yes top of the door next to the either chrome or black door lock rod, about an inch to the left on the pass door and an inch to the right on drivers door next to the rod is where those pieces go. follow lmrs video on youtube for run channel replacement for install tips for that.