I would like to get two 12" subs under my back seat in my Extended cab. I know they make a box for it but i cant find anything on it. Any one know where i can find one? Thanks in advance.

this is a link to a box like you are looking for. we installed one of these boxes in a buddie's 05 last week with 12" kicker cvrs and a fosgate 700.2 amp and it pounds. we took the carpet off and coated it with herculiner to resemble the box we made for my 98.

http://cgi.ebay.com/ebaymotors/1999-2006-CHEVY-Silverado-Extended-Cab-Sub-10-12-Box_W0QQcmdZViewItemQQcategoryZ38647QQihZ020QQitem Z300117035645QQrdZ1

I got my box here

http://www.subthump.com/

Sweet thanks guys. Appretiate it. How did you hook them up to the stock headunit? or did you put a new one in?

we used the stock head unit. it was a non-bose, so we just used a speaker level converter. if you have a bose, look into getting a pac adapter.

where is this speaker level converter?

I have 2 12's under my rear seat and it is so loud. I had the car stereo place order the box not sure who it is made by but it looks factory installed

Nice, thats what i want. What kind of subs did you put in the box, and what kind of amp?

You should check out probox. I have heard good things about them

http://www.proboxrocks.com/products/enclosures/unloaded/chevy/99X212DF/index.shtml