I'm looking for a new head unit, I AM READING the forums on here, but my question is, I have the drop down screen which is connected to the head unit, I don't have any other input for that screen, do the aftermarkets work the same as what I have installed??

 

And what would you recommend 

WHen i purchased mine, it already came with an aftermarket Head unit. The wiring came with a video out or cvbs out which connected to the ceiling screen.

I then purchased a replacement head unit which did not have the wiring and was told to buy a usb to cvbs out which then plugs into the usb cables coming out of the head unit. 

 

So either way should work depending on what you have. As far as im aware most units come with two usb pin outs which you can plug in accessories into. You just need to work out which wire goes  to the ceiling screen