Chevy Duty sells a door rubber kit that has everything you need to do both doors. I just did mine. There's a felt piece that gets attached to the chrome trim on the inside of the door; a rubber piece (sort of like a wiper blade) that goes in a slot on the door and "wipes" the glass on the outside; a rubber seal that goes around the door frame on the cab and is held on by two metal trim pieces that are held on with screws; a rubber seal that goes around the door itself and is held on with glue; a rubber piece that goes on the bottom and is held on with the door moulding; and the "felts" that go inside the door around the window channel.
The kit costs $167.95 and includes everything you need to do both doors. And boy does it make a difference. All the rattles are gone.
If you want, I can take some pictures with the digicam and put them on a web page so you can see what I'm talking about.
[ 01-26-2002: Message edited by: baldeagle ]