[Accelo]

Cost wise, I have my doubts onecan get an original system working for what the aftermarket systems cost. They install easy enough. And you eliminate the mechanical control wires as everything is controlled by a computer and servo motors. I haven't confirmed this but it may be a set it and leave it system. (My vintage air system is installed by not charged yet) It may turn on the heat or air as required to maintain the temperature. One has to change out the hoses, the oil, dryer and the R12 to get the old system functional.
If cost is important I would do aftermarket.
If original is important I would use the GM system especially if I had a air cab to begin with.