I have Clarion DXZ865MP that I was initially going to install into a Dodge Ram, a somewhat easy install indeed, but for a Tahoe, I hear that I am going to need an OnStar adapter, and I plan on adding in an XM Radio Adapter as well. Is this all that I would need to put a new headunit in my Tahoe, or would I need anything else. I am most likely planning on putting new speakers in here at the same time I am going to install the Head Unit, and subs are not much further behind. Is there anything else I would be needing while installing (Except for wires, basic knowledge)... or am I set?