I have been through this problem once and here is what I experienced. Check the rear window seal or the seal that seals water out of the third break light above the rear window. If you sit inside and have someone run a hose over the top of your truck you will quickly see where the water is coming in. For me, I had to remove the headliner because my rear window seal was bad. If you do a search you will be able to find lots more info on this subject as it seems to be a common problem. As far as replacement carpet the dealer wanted way to much. If I remember right the dealer in alaska wanted $400 which didnt include a backing pad. I order replacement carpet from summit racing that included a nice thick pad glued to the carpet for less than $200. None of the holes are cut out of the replacement carpet from summit so it may be worthwhile to keep the old carpet as a template. I didn't have my old carpet when I did mine but with the help of my dad it went in real nice. For the money it is nice automotive carpet. The color match is pretty good. I have a 96 with 125,000 on it so a perfect match wasn't a problem. And after I put my floor mats on it you don't see much of the carpet anyway. Hope this helps!