2001 yukon specs needed

I have a 2001 yukon that I have been slowly upgrading. I have replaced the reciever and the door speakers and added two subs in the back. I have a factory amp and subwoofer on this vechicle. I just found out the other day that my factory sub in the back door panel is still working even though the crutchfield guys said it wouldn't after i replaced the stock head unit. Now I want to replace that factory sub with an aftermarket, but I don't know what specs I need to consider except that it is a 8" sub. what is the wattage, ohms, and mounting depth? Also what size is the two little speakers in the far back columns? They are right by the 3rd row? These probably need replacing as well. One last thing, where is the factory amp located? I might replace that someday. Thank you for any information you might have.

If you are wanting to replace the sub. You will need a new enclosure. The stock enclosure will not be adequate for a aftermarket sub. Same with the amp. As for amp location. In a 2001 Tahoe it is located behind the glove box. Im pretty sure the Yukon would be the same.

ok. well I am not looking for a high power sub or anything that is going to rock my car, simply something that will add a little more sound and hopefully something more in the mid-range freq. I already have 2 alpine subs in a seperate inclosure in the back putting out 1250 watts so a have enough bass, unfortunately the crossover cuts the frequencies out at 200hz which is the highest for those speakers. My factory amp doesn't seem to have enough to push the mids through my door speakers; or just needs to have some settings tweeked on it if thats possible on a factory amp. Crutchfield suggested a Pioneer Premier TS-SW841D which is a shallow mount sub that fits, but they also suggest adding an amp to power that. Is there any other speakers that might fit in that shallow mounted area and could be capable of being powered by the factory amp? Is there a way to adjust settings on the factory amp?

If you already have subs back there. Disconnecting the factory sub is your best option. using it as mid range in the back where you have subs is not going to get you anything worth listening to and will actually trash your stage. Mid frequency range is very locatable. Your mid range should not originate from the back. As for reconfiguring the amp or tuning it, you cant. It is not adjustable.