If your having problems with the radio you can contact http://www.sierra-mc.com/ they are the only people I know who repair these radios. If you want to add mp3 capability then you can use a scoche or audiovox fm modulator to run your tunes through the radio.
if you do not care about the cb/intercom system you could fabricate a new system using the stock pull out box. I just finished mine yesterday with common household tools. it still pulls out with the key and used the factory wire harness.i also added a couple switches for my fork and led lights.