Gday Gents,
Here's a comprehensive list of the bulb types you will need to DIY the lighting on your Gen3's interior. Feel free to add anything or make corrections. This is what i have found in my Gen3 Legacy GTB, some differences may apply to Aus models and wagon/sedan.
Location Type Amount Notes
AT Pwr/Eco Switch T3 Twist Lock 1 T3 (8mm Base) For LED's use ones with a cylindrical diffuser for better light dispersion instead of the low profile square SMD.
Wiper Demister T3 Twist Lock 2 T3 (8mm Base) For LED's use ones with a cylindrical diffuser for better light dispersion instead of the low profile square SMD. (JDM)
Rear Demister T3 Twist Lock 2 T3 (8mm Base) For LED's use ones with a cylindrical diffuser for better light dispersion instead of the low profile square SMD.
HID Level Switch T3 Twist Lock 1 T3 (8mm Base) For LED's use ones with a cylindrical diffuser for better light dispersion instead of the low profile square SMD. (JDM)
Foglight Switch T3 Twist Lock 2 T3 (8mm Base) For LED's use ones with a cylindrical diffuser for better light dispersion instead of the low profile square SMD.
Climate Control T4 Twist Lock 5 T4 (10mm Base) Unit front cover will have to be removed to access 2 of the globe holders. (Cover removed via 4 small screws)
AT Gear Illum. T5 Wedge 1 Remove gear fascia
Glovebox T5 Wedge 1
Ash Tray T5 Wedge 1 Easier to access with stereo out.
Cigarette L T5 Wedge 1 Remove stereo fascia.
Key Barrel Illum. T5 Wedge 1 Remove column covers, slide off barrel illumination unit.
Map Lights 31mm Festoon 2
Puddle Lights 31mm Festoon 2 Stock item slightly smaller but 31mm will fit.
Roof Light 31mm Festoon 1
Rear Cargo T10 Wedge 1 T10 Wedge however it is a big globe. For LED, use something with multiple SMD's.
Dash Cluster T10 Wedge 4 LED's don't provide enough light dispersion. Use a bright white normal globe for best results.
BFM Cluster Rings T5 Wedge 8 Use LED's with built in resistors (Available from Jaycar)