Wonder if anyone can change the lighting from yellow to red?
Yes, it can be done. The challenge is to find the "Red" display board or letters. I have a couple contacts that did warranty work for GM when it comes to these units and they have not seen any in years. The problem here is not just the "Letters" but the other lighting that needs to be changed over as well, for example, the "FM" LED light.
However, I have seen people take a thin (1/8 ot 1/16) piece of "Red" Plexiglass and put it behind the faceplate just in front of the letters with "Okay" success. It does work, just not as bright as it should be. That "Red" lens repair tape does not work at all.