....... If the car truely didn't have a radio, or had a rear antenna (an hence an AM radio) from the factory, there will not be a holde drilled in the A piller forward of the passenger door where the antenna cable went from the interior of the car to the space behind the front fender. If theres a hole there, then the car had a radio when it left the factory.
Are you absolutely sure about that being no hole in the front pillar if there was a rear mounted antenna ordered?
I do recall seeing a rear antenna 67 (option on trim tag too) with the front hole (looked like it was punched) with a plug in it.
The AIM refers to it as 'existing hole' and I figured it was like so many holes punched and plugged based on options.