Where can i get a subwoofer enclosure for 2003 ford sport trac?

i have a 2003 ford explorer sport trac. i have see the single 8 inch or 10 inch enclsures. i want to buy a custom made enclosure that fits 2 or more subs either under, or behind the rear seats. i have seen pictures of this, but i can not find any place to buy an enclosure that has MORE than just 1 sub. Thanks, for any help!Where can i get a subwoofer enclosure for 2003 ford sport trac?Any good custom audio shop should be able to fabricate one. If not, try Crutchfield.