According to the 2004 Ford Expedition Owner Guide :
Low beam headlights take ( # 9006 bulb )
High beam headlights take ( # 9005 bulb )
9005
According to the 2005 Ford Expedition Owner Guide : Low beam headlamp ( # 9006 bulb ) High beam headlamp ( # 9005 bulb )
Halogen.
H1 55W bulb
h 10 or 9005 bulb
The 2004 Ford Expedition has a 4-speed automatic.
9003 or H4, same bulb.
The 2004 Ford Expedition runs on regular unleaded.
H4 twin filament.
See sources and related links below for 2007 Chevrolet Impala headlight bulb part numbers.
I think it's H4.
HB1 / 9004