The should be no wood in the shells of a 2004 model. Some 2002 models had wood, some had aluminum, but to the best of my knowledge, wood was in the past by 2004.
If you are still concerned, Larryjb posted a picture of how to see the frame members, so you can tell for sure if it is wood or metal.
http://www.trailmanorowners.com/foru...ad.php?t=18147
Bill