I installed a classic auto air system in my 68 Barracuda. Nice modern compressor, all new under dash ac box.Everything went together fine.
The kit contains instructions and parts to change over your existing dash mounted ventilation controls to control the ac and the 3 speed fan. The down side is the names molded into the OE dash ventilation plate no longer match up to the actual function. But it is just a matter of remembering the middle position is AC through the new dash vents, full left is defrost full right is floor. IIRC
