Poulan Pro PR550N22SH Muffler?

Hi. I cant find a replacement muffler for this push mower ANYWHERE on the internet. It's as though it does not exist. Does anyone know where I can find this muffler? Please reply if you know where. I have used google, sears, homelife, poulan's site etc and cant find it so does anyone know a Specific site that I can find the muffler for a Poulan Pro PR550N22SH? It's a 961120083 model. Help!!