I am confused by CRX7's post. I have the Sony CDX-M850MP also, and there are NO dials on it, nor does it have a pop-out tray.

Mine fit without ANY issues. Sounds great. You cannot close the S2000 Radio door with the face open. It works VERY well with the Lucid/Modify Sony specific DCI. (They even managed to add speed sensitive volume control if you are into that sort of thing.)

Keep in mind that with this HU there are some things that can ONLY be done with the wireless remote. This makes DJ Cube's mod a little more tricky as you will need to buy another remote. Plus the IR sensor is in two different places (one when open, and one when closed.) That could make it tricky to mount an IR eye.

Here are a couple of pix of mine installed.

 

Whoops, wrong unit, mine is the CDX-MP70.

Sorry guys.