Re: clock display lighting
If it is the same as the light in the OEM radio/cassette deck on a 1990, then the light in the radio is a small soldered-in bulb located inside the radio case. To get at it, you need to remove the radio, then take the outer cover off the radio. You will see the bulb over the display area. As for replacing it, I don't know the specs- could be 12 volt or could operate on less. Reconnect the radio with the cover off and use a meter across the bulb leads. You can then find something similar. Or, as we did on my daughter's jeep, upgrade to a cd player.....