I would call thor with your VIN number.
You never know...maybe their supplier could still source it. Maybe Thor could tell you who made it, the part number, etc...
but yeah, I'm thinking more likely rv salvage like javelin said.
I'll tell you that I had to order one through a dealer from Thor a few years ago after a blow out. it turned out looking ok but wasn't really a perfect fit like a glove thing...took some finagling.