I think all the 03-07 Expy's had a LS 3.73, but not positive. Lemme look it up...
EDIT:
Hmm, seems it was a popular option but not standard on all the models. Will continue looking...
EDIT2:
According to this, it's a 3.73 w/o LS? Granted, the data could be old.
Link
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2003 Expedition XLT 4.6 V8
AFE CAI
Custom Sniper Tune by Matt
Swapped Maggy 18" Muffler
Summit underdrive pulleys