Hi there...last month we announced upgrades were coming to this fleet...
737-800 aircraft improvements
The investment in 43 of Delta's 737-800 aircraft will include the addition of in-seat video with satellite TV, new LED cabin lighting and updated lavatories. The aircraft will be configured with 16 First Class seats, 18 Economy Comfort seats and 126 Economy seats.
When the modifications are complete, Delta's entire fleet of 73 737-800 aircraft will have in-seat video with access to satellite TV and in-seat power throughout the aircraft.
http://news.delta.com/index.php?s=43&item=2232