Larry, is your radio an exact replica like this?
http://www.classiccarstereos.com/product/172001B.html
I have one of these radio's in my 1955.2 3100. Your description sounds just like what my radio is doing. Here's my radio.
http://www.classiccarstereos.com/product/262001B.html
It was manufactured by Antique Automobile Radio Inc. 700 Tampa Road, Palm Harbor Florida. I bought it from spautoradio in Wisconson on Ebay.
Let us know what you find out.

Brian
1955.2 3100 Truck
The older I get the more dangerous I am!!!!!