05 chevy silerado bose,adding sub

I have installed a sub on a 2003 silverado with bose before.  I know that the output of the wires going to the front and rear speaker have already been crossed over, and you can not get a low level signal from them.  I had to rip out the entire center console to get to the wires going to factory sub, so I could get a low level signal.  Dose anyone know of an harness or an easier way to tap into that low level output coming out of the factory amp, under the console.  Maybe someone could give me a wiring diagram of the wires coming out of the amp and i could tap into them there.

Thanks

billy

you dont need a low frequensy signal to get your sub working if you adding another amo for the sub then you can just click on the LPF filter and your set the lpf filter tskes out all your high and makes a low fequency signal to your sub. you can buy a converter at any best buy or stero shop. you rjust going to tape into one of the sopeaker wires then gounr out the converter