DVD system question

So I just bought a 2008 sierra sle with lots of modifications already done by the previous owner. They include an oem console up front instead of the bench seat, pioneer avic-d3 in dash dvd player, and a monitor mounted to the ceiling that turns on when the head unit is in video mode. The console still has the controls for the rear seat, but does not work due to the aftermarket head unit.

My question is, does anyone know where to find a seperate dvd player that will fit where the rear controls go in the console? I would like to find one that fits and will allow me to run a seperate dvd to the rear monitor for the kids so I can listen to music or what not while they watch their movie with headphones. Thanks a ton for any help!