On a 1995 940 SW what are the two boxes under the floor decking?

On both sides under the floor panel to access the tail lights there are black plastic boxes about 8" cube. The bottom of the boxes are open, and have what feels like foam rubber on one side.

Thanks.

I was in the back of the wagon with the hatch closed and I noticed one of the boxes flopped a little when a door closed so I just assumed they were pressure vents.

Edit: There are two vents on the top trim just behind the seat back that seem to funnel to the boxes. Just an edumucated guess on the functionality.
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Tom F. Three Bricks, maintain two more.

The boxes in the storage area are vents. The car is real tight to keep out road noise so to allow the air brought in through the AC/Heater a place to go they added those things. They have flappers to allow air to pass out but close to incomming air. If you look for them you will find them on both wagons and sedans in all the 700/900/S/V/90.

The little vent looking things behind the seats may work as vents but the real purpose is for a seat belt passage for the 3rd seat. With the 3rd seat, the fitting/plug is a different design.
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'96 965, 16' wheels, Michelin Pilot Sports, rear 18mm bar + Koni, 201 HP cams, 132K. Put 200K on '85 745 TD.