I had mine done by Mr Heaterbox. They use Aurora Design hardware to replace the guts of your stock unit. It looks original but has a ton of features that are modular so you can only add the components you want. AM/FM tuner, AUX input, Bluetooth for music playback and even taking calls, USB stick support for music and phone charging, HD Radio. It has 4 speaker outputs and sub pre-amp outs. Really is a nice setup. I found an AM/FM for my 72 and sent it to them. The AM/FM knob changes bands, tone knob works. Push buttons work. I installed the AUX input, call answer/end button and USB in the blank area beside the cigarette lighter
Here is a link to their website
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