We just sold our 2006 21SS at the beginning of this year. If memory serves me right, somewhere in the middle of the 2006 model year there were two changes we noticed that we wished we would have had. One was the camper itself was raised higher on the trailer frame. I know I'm not saying that quite right, but what we noticed was that we had to step up into the dinette on our model, where on the updated model the floor was flush. The other thing we noticed was the addition of windows in the short walls of the slide. That's a small thing, but it would have been nice. The 21SS was our first family camper, we LOVED that trailer. We really enjoy our 23SS too, but the 21SS really has a warm spot in our heart!