I don't know but we are going to put paneling of some kind in the back where hubby decided to take it off to beef up the ladder on the outside. We doubt we can put back up what is in there so going to go to Home Depot or Lowe's and find something close. The RV place had some, it was $50 a sheet and really ugly.
You likely won't get an exact match but hopefully something similar.
Good luck