As Leon has said, the floorplan should be basically the same. The location of the air conditioner maybe on the roof of the back shell or in the lower cabinets. I know the 2619 in 1999 had it in the cabinets. I don't remember which models had it on the roof in 1999. If it has the spare tire carrier it will be mounted on the back bumper. The new models it is mounted underneath the front body. The wheel wells maybe square instead of rounded which is not ideal for a tire blow out. I modified my wheels wells. You may check it out here:
http://home.comcast.net/~trailmanor/whlwell.htm