your headlight assembly is a molded and glued one piece system that the different light pods screw into. my suggestion is to look on line for a complete replacement. had the same mosture problem with the left hand light system on our 2005 malibu maxx. you can replace your lights with either stock units or aftermarket ones
http://shop.ebay.com/i.html?_nkw=2004+chevy+malibu+headlights+&_cqr=true&_nkwusc=2004+cheyy+malibu+headlights&_rdc=1
hope this helps