What bulb do I need for the dash illumination in a 1979 Volvo 244DL?

I disembled the instrument cluster to replace two burned our bulbs in the car. When I took them out of the socket and took it to Advance, they did not have a bulb to match. Please note that this is not the bulb for a warning light but the light that sits above the cluster to illuminate the gauges at night with the headlights turned on. i have now been hunting in vain on the internet for hours looking for a correct replacement. The bulb is a very small push and turn type bulb. any help is greatly appreciated!