Jeff,

Yes, it is possible to convert with modern parts - $300-$400 by a radio shop.

http://www.vintageautoradio.com/ind...amp;view=article&id=46&Itemid=55

It is also possible to by a new, modern AM/FM 12v that looks like an original GMC radio (and ports for iPods, etc) - $450-$550 without speaker.

http://www.vintageautoradio.com/ind...&option=com_virtuemart&Itemid=67

Tim