My rear muffler started rattling recently in my 94 Disco. I checked it out and it has a one inch hole and the exhaust pipe connected to it has a few holes close to where it connects to it and feels like old tried up masking tape. It rattles at low speeds and when it's idle (sometimes it doesn't when I'm at a stop light). I checked all over the exhaust system and couldn't find any loose bolts. The cats, y pipe, and muffler under the truck look and feel like they're in good shape. Anyone else have this problem? Are the muffler and exhaust pipe just trying to tell me they need to be replaced?