I would call crutchfield.com or go to a local shop and find out what amps can except speaker wire instead of RCA, then use the rear speaker output for your subs, but then you have the problem of powering all of your door speakers. You can't splice RCA and running more then one speaker off of the same wire willproduce bad sound quailty. If you really wana stay stock use the box in the rear cargo door, and the amp in it and get these
http://www.crutchfield.com/App/Produ...1%5d6-1%2f2%22or justsave some cash andupgrade the head unit. it was the first thing did in my 96 disco, but i like the idea of not haveing a big box in my cargo area, so i might use that last sugestion or remove one of the floding jump seats for a place for a box. good luck tell me how it goes.