I got it off of eBay. Just type in the year of your 300 and stereo. I didn’t buy a rear view cam but I found a video here on RU-vid explaining how too install the rear view camera. Just type it in. The steering wheel control was automatic when connecting all connections. Bluetooth calling works as long as you connect the mic that comes with the setup.
There’s 2 plugs on the stock head unit one rectangle one and one smaller square one one only one plug in on the aftermarket radio which is the bigger rectangle one what does the smaller square one do cause I actually bought this exact head unit and it wouldn’t work does the square plug have something to do with it?