I have a 2002 wrx and im sure the is similar. The cluster came out super easy with just 5 screws getting to it. 3 plugs undone and out comes the cluster. On the back side I found a bunch of bulbs and sockets.
Ive been workin on my dash lights. Learning the hard way cause I fubar my instrument cluster by removing the green film. With green film removed and replacing stock bulbs with blue bulbs, not bulb condoms, the result was NO different. The lights were a little brighter but overall the color was still the same. Maybe teal-ish. Overall I had the same color, broken cluster, and $100 out of my pocket for another cluster.
I know now that LED is the only way to go if you want a blue dash. I however have 2 different T10 blue LEDs still in the mail waiting to see if they will fit and such. Im hoping T10 LEDs was pop right in and give a blue glow even with the green film on my new cluster. I know #74 bulbs or LEDs will fit in my bulbs sockets on the cluster.
If anyone is interested I will post pics of how I did everything and what each setup looked like.
And if anyone has done this I would like to know exactly which LEDs you used and a picture.