My 51 Kaiser came with no radio. I took the delete plate off the dash, installed hinges on it, and put a modern radio behind the delete plate. I swing it upward and you have a modern radio sitting beind it.. I use a 6 to 12 volt inverter. The set up uses a under dash 12 volt antenna boost. Works okay in and around the city (Los Angeles) but out on the open road, not much reception. The antenna has a splitter, and I have a magnetic mount antenna in the trunk if I want better reception. I don't know if the hidden boost antenna does much or if it is the antenna in the trunk that is picking up the reception.
Radio Shack has a Y splitter that allows you to connect to antennas.