I recently changed some bulbs in my instrument cluster,only 2 were burned out but I changed them all since I alredy had the cluster out (plus I am upgrading to a slightly higher wattage bulb).I work in a truck repair facility and recently came across some bulbs that are identical to the volvo dash bulbs,the plastic base is exactly the same and they are even made by the same manufacturer (osram-Germany)the only difference is the colour of the base-these are yellow and the volvo ones are blue-the trip computer is black.Also the volvo bulbs are 1.2w and the ones I found are 1.5w not a huge difference but they should last longer.I also changed the 4 larger bulbs for the guages these bulbs can be found at any automotive shop,you dont have to pay volvos price!.
The bulbs are #194 -use the original plastic base,just pull out old bulbs and insert new ones.I purcased 2 boxes of the small bulbs so I have extras that I probably wont need,If any one wants them my cost is about $2.15ea.US(volvo is about $2.90ea.) e-mail me if interested.