Ok so I searched and I didn't find the exact thing I was looking for.
The Deville is notorious for non factory head units, thats cool. I like the factory HU. I am planning on hooking subs and an up. Where should I tap for a signal? Rear speakers or somewhere behind the HU? And also would I risk getting any problems that others have had when they have screwed with their HU? Like alarm, blinking lights ect ect? Or would it just be a simple pop a couple of wires in and I am done?