Good news!!!!

I also have a 2003 ford expedition and have located a place that sells these units seperate.

The web site is radiosandmore.com

the units are around $50 each.

Please make sure your dvd player has one ofof these little glass windows on each side of your dvd player. IT MAY ONLY HAVE 1 WINDOW ON THE RIGHT SIDE. THIS IS AN INFRA RED WINDOW THAT ALLOWS FOR THE WIRELESS HEADPHONES TO WORK.

IF YOU DO NOT HAVE THESE THEN YOU MAY BE SET WITH THE WIRED
HEADPHONES