SL/R129: Instrument cluster back illumination went out

I've got faulty instrument cluster back lights on my 1997 SL320.
At night only 2 gauges out of 5 have working lights, the others are blind.
I've seen the walkthrough on how to replace them, but I wonder where to buy the lights itself. Do I need to specifically buy them from MB or can I put any kind of light bulb?
If I need to take them from MB, what's the part number? How much do they cost?
Thank you in advance, regards!



