Ripped off from NASIOC in the most blatant way possible.NOTE: When using 168 bulbs, you can replace them with the brighter 194 bulbs. This is practically the same bulb, just draws a bit more current which in turn makes it a brighter bulb.
MY98-2001 Impreza
High & low beam headlamp: H4 (also called 9003)
Parking light: 194
Front turn signal: 1156, 194
Rear turn signal: 1156
Tail light: 1157
Stop light: 1157
High mount stop light: 912, 921
Fog/Driving light: H3-55W
License plate: 194
Back up light: 1156
Front sidemarker: 194
Rear sidemarker: 1157
Ash tray: 74
Map light: DE3175
Dome light: 168, DE3175
Trunk/Cargo area: 168
Instrument-general: 158, 74
MY02-03 Impreza (Non Wagon)
High & low beam headlamp: 9007
Parking light: 168
Front turn signal: 1156
Tail light: 7443
Stop light: 7440, 7443
High mount stop light: 921
Fog/Driving light: H3-55W
License plate: 168
Back up light: 7440
Front sidemarker: 168
Rear sidemarker: 168
Ash tray: 74
Map light: 168
Dome light: DE3175
Trunk/Cargo area: 912
MY02-03 Impreza (Wagon)
High & low beam headlamp: 9007
Parking light: 168
Front turn signal: 1156
Tail light: 7443
Stop light: 7440, 7443
High mount stop light: 912
Fog/Driving light: H3-55W
License plate: 168
Back up light: 7440
Front sidemarker: 168
Rear sidemarker: 168
Ash tray: 74
Map light: 168
Dome light: DE3175
Trunk/Cargo area: 921
MY04-05 Impreza (Non Wagon)
Low beam headlamp: H1-55W
High beam headlamp: 9005
Parking light: 168
Front turn signal: 7440
Tail light: 7443
Stop light: 7440, 7443
High mount stop light: 921
Fog/Driving light: H3-55W
License plate: 168
Back up light: 7440
Front sidemarker: 168
Rear sidemarker: 168
Ash tray: 74
Map light: DE3175
Dome light: DE3175
Trunk/Cargo area: 921
MY04-05 Impreza (Wagon)
Low beam headlamp: H1-55W
High beam headlamp: 9005
Parking light: 168
Front turn signal: 7440
Rear turn signal: 1156A
Tail light: 7443
Stop light: 7443
High mount stop light: 912
Fog/Driving light: H3-55W
License plate: 168
Back up light: 7440
Front sidemarker: 168
Rear sidemarker: 168
Ash tray: 74
Map light: DE3175
Dome light: DE3175
Trunk/Cargo area: 912
MY04-05 Impreza (STi)
Low beam headlamp: HID-D2R
High beam headlamp: 9005
Parking light: 168
Front turn signal: 7440
Tail light: 7443
Stop light: 7440, 7443
High mount stop light: 921
Fog/Driving light: H3-55W
License plate: 168
Back up light: 7440
Front sidemarker: 168
Rear sidemarker: 168
Ash tray: 74
Map light: DE3175
Dome light: DE3175
Trunk/Cargo area: 921
MY02-03 Forester
High & low beam headlamp: H4 (also called 9003)
Parking light: 168
Tail light: 7443
Stop light: 7443
High mount stop light: 912
License plate: 168
Back up light: 921
Front sidemarker: 168
Ash tray: 74
Map light: DE3175
Dome light: DE3175
Trunk/Cargo area: 168
MY04-05 Forester
High & low beam headlamp: H4 (also called 9003)
Parking light: 168
Tail light: 7443
Stop light: 7443
High mount stop light: 912
License plate: 168
Back up light: 921
Front sidemarker: 168
Ash tray: 74
Map light: DE3175
Dome light: DE3175
Trunk/Cargo area: 168
MY02-03 Legacy GT
Low beam headlamp: H1-55W
High beam headlamp: 9005
Parking light: 1157A
Front turn signal: 1156A, 1157A
Rear turn signal: 3157LL
Tail light: 3157LL
Stop light: 3157LL
High mount stop light: 921
Fog/Driving light: H3-55W
License plate: 168
Back up light: 3156LL
Front sidemarker: 1157A
Map light: DE3175
Dome light: DE3175
Step/Courtesy light: 194, DE3021
Trunk/Cargo area: 2825
MY02-03 Legacy Sedan
High & low beam headlamp: 9007
Parking light: 1157A
Front turn signal: 1156A, 1157A
Rear turn signal: 3157LL
Tail light: 3157LL
Stop light: 3157LL
High mount stop light: 921
Fog/Driving light: H3-55W
License plate: 168
Back up light: 3156LL
Front sidemarker: 1157A
Map light: DE3175
Dome light: DE3175
Step/Courtesy light: 194, DE3021
Trunk/Cargo area: 2825
MY02-03 Legacy Wagon
High & low beam headlamp: 9007
Parking light: 1157A
Front turn signal: 1156A, 1157A
Rear turn signal: 7440
Tail light: 1157
Stop light: 1157
High mount stop light: 912
Fog/Driving light: H3-55W
License plate: 168, 194
Back up light: 1156
Front sidemarker: 1157A
Map light: DE3175
Dome light: DE3175
Step/Courtesy light: 194, DE3021
Trunk/Cargo area: 912
MY02-03 Legacy Outback Sedan
Low beam headlamp: H1-55W
High beam headlamp: 9005
Parking light: 1157A
Front turn signal: 1156A, 1157A
Rear turn signal: 3157LL
Tail light: 3157LL
Stop light: 3157LL
High mount stop light: 921
Fog/Driving light: 9006
License plate: 168
Back up light: 3156LL
Front sidemarker: 1157A
Map light: DE3175
Dome light: DE3175
Step/Courtesy light: 194, DE3021
Trunk/Cargo area: 2825
MY02-03 Legacy Outback Wagon
Low beam headlamp: H1-55W
High beam headlamp: 9005
Parking light: 1157A
Front turn signal: 1156A, 1157A
Rear turn signal: 7440
Tail light: 1157
Stop light: 1157
High mount stop light: 912
Fog/Driving light: 9006
License plate: 168, 194
Back up light: 1156
Front sidemarker: 1157A
Map light: DE3175
Dome light: DE3175
Step/Courtesy light: 194, DE3021
Trunk/Cargo area: 912
MY04-05 Legacy Sedan
Low beam headlamp: H7
High beam headlamp: 9005
Parking light: 3157A
Front turn signal: 3157A
Rear turn signal: 7440
Tail light: 7443
Stop light: 7443
High mount stop light: 7440
Fog/Driving light: H3-55W
License plate: 168
Back up light: 921
Front sidemarker: 3157A
Rear sidemarker: 7443
Map light: DE3175
Dome light: DE3175
Step/Courtesy light: DE3021
Trunk/Cargo area: 2825
MY04-05 Legacy Wagon
Low beam headlamp: H7
High beam headlamp: 9005
Parking light: 3157A
Front turn signal: 3157A
Rear turn signal: 7440
Tail light: 7443
Stop light: 7443
Fog/Driving light: H3-55W
License plate: 168
Back up light: 921
Front sidemarker: 3157A
Rear sidemarker: 168
Map light: DE3175
Dome light: DE3175
Step/Courtesy light: DE3021
Trunk/Cargo area: 912
MY04-05 Outback Sedan
Low beam headlamp: H7
High beam headlamp: 9005
Parking light: 3157A
Front turn signal: 3157A
Rear turn signal: 7440
Tail light: 7443
Stop light: 7443
High mount stop light: 7440
Fog/Driving light: 9006
License plate: 168
Back up light: 921
Front sidemarker: 3157A
Rear sidemarker: 7443
Map light: DE3175
Dome light: DE3175
Step/Courtesy light: DE3021
Trunk/Cargo area: 2825
MY04-05 Outback Wagon
Low beam headlamp: H7
High beam headlamp: 9005
Parking light: 3157A
Front turn signal: 3157A
Rear turn signal: 7440
Tail light: 7443
Stop light: 7443
Fog/Driving light: 9006
License plate: 168
Back up light: 921
Front sidemarker: 3157A
Rear sidemarker: 168
Map light: DE3175
Dome light: DE3175
Step/Courtesy light: DE3021
Trunk/Cargo area: 912
This concludes the Bulb Replacement Guide. I hope this will help you figure out what bulb you need. I would strongly recommend looking at your owners manual and checking the bulb # before purchasing a bulb. If you have any questions, feel free to PM me.
Thanks for reading, and have a great day.