I found a single 10" sub box on ebay. But for dual 10"s you will need to have one made. I got my box made by a guy on this forum, I forgot his name. Click on the link in my box, I like it. Some local shops where quoting me 150-200 for the box I got mine shipped for less than half that!
depending on the box you may have to move the seat up a little, I did.