520-system unit airflow cards

We are going to remove all of the 5326 and 5327 disk drives from our 520 
system unit.  The 5327's are going to the 570.  The 5326's will be swapped 
for 5327's for the 570.

1 - Will airflow cards from a 570 work in the 520 to fill the empty slots? 
 Our CE seems to think not.  And he seems to recall that what few airflow 
cards we have laying around came from the 570.

2 - What is the part# for the 520 airflow cards?

Also, all of these drives in the 520 system unit were for a lpar that was 
never fired up.  Never even had lic loaded on it.  CE seems to think it's 
best to power down the 520 prior to removing the drives.  He checked with 
support on that and they concur.

Rob Berendt