If you want a new set, I found reference to it at:
The 3000-pound capacity Ramp Doors are available with multiple flooring options and are easy to install to any rear ramp door.
www.lci1.com
Our rail set for the rear ramp is a MorRyde product, and the side patio is also a MorRyde. But these are different sizes, so measure.
But there are some RV surplus places around Goshen, Ind. area:
rainbowvarietystore.com
www.johnsonssurplus.com
Johnsons is the newest place. Bontrager's has been around the longest. Last August when we were there in the area Rainbow did have a set in their store.