They could be bulbs or LEDs, they are designed not to be replaced; however, they can be. If you are good with a soldering iron and not worried about tearing the components apart.
I replaced all the component bulbs (radio, HVAC, I/P computer) and all switch bulbs on my Vette with Blue LEDs. Easily to disassemble the components and access the bulbs. Very hard to install LEDs in place of bulbs.
