The official US Armed Forces records show only one death in December of 2003, in regards to Operation Enduring Freedom (Afghanistan conflict). The death was not combat-related and did not even happen in Afghanistan.
Army Sgt. Theodore L. Perreault
Army Sgt. Theodore L. Perreault of Webster, Mass.; assigned to 1st Battalion, 181st Infantry Regiment, Massachusetts National Guard (attached to Joint Task Force Gitmo), Worcester, Mass.; died of a non-combat-related cause on Dec. 23, 2003, at Guantanamo Bay, Cuba.
The 10th Mountain division has a list of all of their fatalities here:
Fort Drum - Fallen Warriors
There were 40 deaths in Dec 2003 related to Operation Iraqi Freedom.
More documents on Military Deaths:
404 - File or directory not found.
http://www.fas.org/sgp/crs/natsec/R41084.pdf