Ranger Edge Tonneau Cover

I have a 2001 4.0L Ranger Edge with a center split hardshell tonneau cover that was stock with the truck from the dealer. My rear lock failed while driving down the highway and it snapped the lifting pistons. The truck manual only talks about maintence and does not mention aything about replacing the parts. Does anybody have any idea where I can get replacement parts? I purchased the truck in California and now I live in New England and the local dealer here wasn't very helpful.