Casefarmer is probably referring to the Total Cleaning Area. Deere's is 7097sq. in. in the 9860, 9760, and 9660.
and the 9560 is 5595 sq. in.
http://www.deere.com/specsapp/CustomerSp....=FR&pNbr=9860SH
http://www.deere.com/specsapp/CustomerSp....=FR&pNbr=9760SH
http://www.deere.com/specsapp/CustomerSp....=FR&pNbr=9660SH
http://www.deere.com/specsapp/CustomerSp....=FR&pNbr=9560SH
and the 9560 is 5595 sq. in.
http://www.deere.com/specsapp/CustomerSp....=FR&pNbr=9860SH
http://www.deere.com/specsapp/CustomerSp....=FR&pNbr=9760SH
http://www.deere.com/specsapp/CustomerSp....=FR&pNbr=9660SH
http://www.deere.com/specsapp/CustomerSp....=FR&pNbr=9560SH