I swap out a CD30 for a CD30 MP3 and the 2 line display for the the 3 line version. I wanted to be able to get a lot more playback time for music and podcast type audio recordings without having to mess about with CD's while on the go. I could use the line in an hook up an MP3 plater or phone, but I didn't want extra devices and wires. And I also wanted something tactile to use that didn't need looking at while driving. So the stereo upgrade made the most sense and was pretty cheap to do.
There were some problems I had when doing this as the first stereo/display pair I had was not a matched pair so was not usable. So a clip or two in the footage may be inconsistent. But the general process is pretty much covered.
If the head unit is not paired with the original display it came with, then "Display Safe" will be shown and the display will not show any information from the stereo/radio or onboard systems. This is a security measure to prevent head units being stolen to "upgrade" an existing installation.
If you are buying 2nd hand make sure to get a matched display.
