Rear air intake on 1972+ up limousines

[D.Smith]

Up thru 1971 the Fleetwood Series 75 cars had two rear fresh air intake vent openings for the rear Climate Control system.  In 72 they were gone.   How did the system get fresh air then?   
I checked my books, no mention of the change.  Aside from comparing the shop manuals between 71 & 72 that is.

Anyone know?  Please no guesses.  I can do that myself.

71 and 72 comparison photos below.

[V63]

I knew The long time owner of that maroon 71 formal.  It was special ordered with full red leather formal front. Gold/beige  embroidered cloth rear. Very low miles. A matching 71 Cadillac station wagon was somehow associated with it as well. He owned them for decades.

[Roger Zimmermann]

From the '72 shop manual:
"This assembly draws car interior air from the the rear compartment through the package shelf"
Maybe this makes sense to you.

[D.Smith]

From the '72 shop manual:
"This assembly draws car interior air from the rear compartment through the package shelf"
Maybe this makes sense to you.

So it just recirculates cabin air?  I hope there weren't a lot of cigar smokers!     LOL

[Roger Zimmermann]

If I reread the sentence, it seems so, but it would make no real sense.

[The Tassie Devil(le)]

Don't forget that the 1972 year was the first of the vents in the door pillar in front of the rear quarter panel.   But I think this was for outgoing air to relieve pressure within the cabin.

Bruce.