Here is a pic of what I am thinking about buying (sorry about the pic quality but it is all that the person has on the website)
When I go to JapanParts for their part to replace the Head Unit so that you can add your own after market set, they state that you must choose type A-C or D-F ? Is this an absolute requirement because from looking at the new head unit it looks like it would just be a simple matter to slide out the old and slide in the new.

