Hi Fred and Eileen!
Here is what I found when shopping in Jan 2013. The Slide-in-a-slide has been available on the 36RL at least as far back as 2012. It was a Queen. If you didn't get the slide-in-a-slide, you could get a King.
Here is the weird part - I was standing in a 2012 36RL slide-in-a-slide with a KING bed at the RV show. It was a queen at the head of the bed where it fit in the slide, but expanded to a king the rest of the way. We ordered ours that way, and Leonard "Redwood Rep" called us right back and explained that was a special made mattress they tried, they didn't like it and quit doing it, but if we really wanted it he would find us a mattress in inventory to use in ours. He said they were miserable to make the bed and when the slides extended it pretty much pulled stuff off the bed. You may find some used ones out there with a King slide-in-a-slide, but they are rare.
We took his advice and ordered the King without a slide-in-a-slide. It works, but the slide is shallow on a 36RL (more shallow than others) and so floor space is pretty tight at the foot of the bed compared to others. Nothing we can't live with, but if we get another, it will be the new 38RL with a King slide-in-a-slide.
Brad & Dory - Lone Tree, CO
CURRENT - 2013 Itasca Meridian 42E/2013 Wrangler 4dr Sahara
SOLD - 2014 Redwood 36RL/2014 F350 DRW