No one masses produces a spare tire well box that I know of... because the internal air space requirements for differant subwoofers varies... so the design of the box will very per subwoofer. You would have to have one made. You have to look around differant shops because cost is gonna depend on how you get it done. and you done HAVE to use fiberglass there you can just use a normal wooden box and drop the stock carpet over it, cut a hole in it for the woofer and presto... looks just like you got a fiberglass box
