[Verne_Frantz]

Ken,
Radios were one of the items (like OSRV mirrors) that many dealers installed themselves to make a little more profit than if the car was RPO'd with a radio. Sometimes the dealer would use the Delco unit too because he could buy it through service parts, then charge the customer the full list. HE made a larger margin on it that way than if he put it on the car order.
There are a couple ways to tell if the radio was a factory installation or dealer. The factory die punched the hole for the antenna, where the dealer used a hole saw. Also, rear antennas were installed before the trunk spatter paint, so a factory installation would have some overspray on the base of the mast and the bracket that held it to the inner wheelhouse lip in the trunk.

Verne