Can I use the wiring for the stock subwoofer to control my 12" MTX molded powered sub.

 

No. that wiring will not handle even close to what your 12" sub will, and the stock amp wont push it at all. you need to use an aftermarket amplifier and aftermarket wiring kit, and use a line-out converter to get signal to your amp (attach the line out converter to your stock sub wires to get low signal).

 

Thanks for the info What parts will I need exactly and where can I pick them up?