OEM radio and sound system
 

How can you tell which of 4 systems you have? My 2009 has 4 speakers a CD player and a cassette player. I'm considering a kennwood

Your best bet to matching up a new one is to consult Crutchfield's online catalog.

Kenwood DNX996XR
 

just pulled the trigger on this head unit, now I need advice on camera’s and Sirius deals, maybe some ideas on usb locations. Maybe even a dash cam.

I'm in need of a good sound system -- need something decent, like a Kenwood.
What did you get to fit your dashboard ?? My '95 Grand Marquis has the same size dash opening as your '99.
I have had Kenwood rigs in the past, and was very happy with the Kenwood brand.
I know nothing about installing auto stereos - will have new unit professionally installed at Best Buy.

Subwoofer
 

Update, also got kicker ds68 speakers with plan to add a sub, considering 3 ways, 1-town car factory sub, 2- build one out of a 12*12 sonatube, or 3- buy a spare tire sub JBL, Cerwin Vega any thoughts. I’m leaning towards the JBL