passenger window rattles when down

[ras]

Any body knows what causes the passenger window to rattle when its rolled down?

[ras]

Ok I figured it out there was a screw missing from one of the tracks at the bottom of the door.

[Steve]

What year was your Silverado? Wonder how the screw came out of that.

[ras]

its a 99 z71. I think someone replaced they regulator i think that is what its called and just didnt replace the screw.