Sorry ron, never notified you asked me a question.... hope you found what you need..
That's alright, no worries. I decided to get in there and see what's there. Apparently there's a plug that has 'everything' connected already, except for the video signal (RCA), but onstar etc is there, even though the car doesn't have XM/onstar etc.
The mirrors are plenty available too, approx $100 for one in "A condition"
Originally the idea was to get a nicer mirror that dims, with traffic from behind at night. Especially when a car approaching from behind had their brights on. Going for a mirror that also has the LCD display is just a few $$ more. ... and actually, it doesn't have to be used for video, one could do something else with that display too.
Ron