tx/rx light replacement, what do I need?

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Before anyone asks, I did search and couldn't find anything on this. I've got a Cobra 29 chrome, and what I want to do is can the green tx/rx light for a blue one to match the rest of the radio. I know I've seen this done, I just don't know exactly what light I need or where I can get one. I think it's either a 3 or 5mm but I also don't know if I need common cathode or common anode. Any help y'all can offer is appreciated.