Factory Air Condition on Early "S" - "Rare" option ?

Could someone please tell me more about Factory Air in early 911's.
I searched around, but found no previous threads about the subject.

I've seen dealer installed air and had never actuallly seen factory installed air. What I didn't realize was that the front pan was completely different to accomodate the blower. In addition, the condenser was placed under the pan and protected by skid bars. Looks a little funny with the spoiler.

How rare is factory air? Anyone know approx. how many early "S" cars were equipped with air? And lastly, How does factory air effect value on the car? Is it an add or subtract??

Thanks!