A/C became optional equipment on our trucks in '65. Obviously if it is done very neatly it's factory. Should be two round vents in the center of the dash with some other misc. vents scattered around with a/c appropriate controls. I agree with what zenish is saying. If you can fix it yourself, then go for it, but, if you're going to have to send it somewhere, be aware that the price tag is going to gain some weight real quick.
Matt
