After enduring those incessant rattling windows for years, I finally found a simple fix - other than stuffing them with bits of folded paper.

On my '91, with the slider windows opened, you can look at the forward track/window seal and see an obvious gap in the seal sections at the midpoint area of about 8 inches in length. I used some gray, round, lightweight, closed cell weatherstrip that was lying around the shop. Using scissors, I cut a lengh of this weatherstripping section in thirds - lengthways. Press this into the bare section of the track using a blunt tool- leaving the rounded edge facing out. This affords just enough resistance to the slider window to keep it securely in place on its fastener. Voila! No more rattles.

 

On my 1995 there are black pieces of rubber placed into the track to keep the window from rattling, though they come out easy sometimes. Maybe you just need to pop down to the Ford dealer and get a set?

 

Thought of that, but sold as complete assembly. Way pricey.

 

Then I am glad I always made sure they got pushed back in