A/C cars have a more powerful blower motor than the non A/C cars. There is a cooling tube that feeds a small amount of the blower air back through the motor to help cool it. The first 2 pictures show the cooling tube pieces.
The suitcase is mounted to the firewall using a combination of screws and studs. The third pic shows a stud that screws into a hole above the blower opening. This stud had a big gob of sealant around it on both sides of the firewall. There are also 2 studs attached to the heater core box on the inside of the firewall. They poke through the firewall and secure the inside edge of the inner suitcase. These 2 studs are visible on the right side of the fourth pic.
As you can see in the last 2 pictures, it might be a good idea to remove the suitcase for cleaning if you ever get a chance. The evaporator can get plugged with leaves and other debris sucked in through the cowl. In my car, a mouse had created a large nest in the suitcase using batting from the seats.
