Okay I bought a used P1000 with the hard cab last summer and noticed the rattleling windows. I asked the guy I bought it from if the windows always rattled. He said yes. Anyway after buying it and getting it home , I took the doors apart and found that the rubber pieces that go into the tracks to prevent the window rattle had slipped down the track and into the inside of the doors. I my solution was to slide the rubber back up and I used silicone in behind the rubber and the track to keep the rubber from sliding back down. Pull your doors apart and you'll more then likely find the rubber inside.