before you go through the time and expense of replacing the window you may want to invest about 7 bucks each on the meguiar's mirror plastic cleaner and polish. you use the cleaner first and it will probably take several runs to get it as smooth and clean as possible. then the polish coat to bring out the translucence. i bought a used 98 with a half weathered rear window and now it looks almost like new. i wouldn't have believed it if i hadn't done it myself.
got the mequiar's at a marine supply store. for 14 bucks it's worth the try.