ill install em for like $80.
but u need brackets. those dont look like they have any, u can make some or buy some tho. or put em in like that with foam glue
this is how it works.
do u have a brain for your in dash (under passenger seat or something)? if not then its more work.
once u have the monitors installed, you put each of those silver boxes (brain) under each seat or where convenient. 1 wire goes to the other brain and the other wire goes to the back of your HU or the brain for your HU