HID Headlights 9006 6000K
EDIT: THESE ARE 9007 BULBS, NOT 9006
These will fit any 99-04 Mustang GT/Cobra/Mach 1
They are low beam only.
Paid well over $170 for them new.
Asking $80 shipped for them. Don't have any pictures right now as they are on the car still.