Mine was cracking, so I measured the old one and bought a new one on Amazon. It was around $90, which seems like a lot for a piece of plastic. It's a little work removing most of the sealant to remove the old shell, but after that it's not too bad a chore. And I think the new cover is made of a higher quality material, too.
2011 Dodge Ram 1500 HEMI Quad Cab
2011 Jay Flight 26BH