One of the several Rialta forums on Yahoo groups has a post by a woman who made a replacement from regular plastic shower curtain and snaps (from Joann's fabrics). Don't have the URL and I quit the group. Very simple to put first snap in, snap it to inside snap on shower. Move to next inside snap, install the mating snap on the curtain at that position, repeat until all inside snaps have a mating snap in the curtain.
If you're interested in true Winnebago parts try
http://www.winnebagoind.com/pr..... Will try to find the Yahoo group URL