That is good to get those pictures. Because of your mention of it coming out of the larger truck, I thought it might be the model that is quite different. I will look at my diagrams etc. and my spare radios to try and get you your information.
In around 1958, a lot of the car radios including GM, went to a hybrid tube /transistor design. The tubes were all low voltage, as in 12 volts and the output used a power transistor on the back. In this case there was no need for a vibrator or power transformer. Your radio is of the pure tube design with the vibrator.
