The '05 Armada doesn't have the DVD wiring harness there...but the inputs are still on the back of the Head Unit. Search the posts and you will find a lot about wiring up an aftermarket DVD player.
http://www.clubarmada.com/forums/showthread.php?t=517
http://www.clubarmada.com/forums/showthread.php?t=196&highlight=wiring+diagrams
Check these out for some helpful hints. I don't know if the Sat radio will play through the headphones in the back though.
http://www.clubarmada.com/forums/showthread.php?t=517
http://www.clubarmada.com/forums/showthread.php?t=196&highlight=wiring+diagrams
Check these out for some helpful hints. I don't know if the Sat radio will play through the headphones in the back though.