Hydro Fan 7" - 10 Blade fits Ferris ISX800 Zero Turn Mowers with Hydro-Gear ZT-3400 Transaxle.  HG 53821.

Fits the left and right hand transaxles which are part numbers 5106646 & 5106647.

Fits these Ferris Models:
5901745 - ISX800 Series w/ 61" Mower Deck (ISX800KAVE2661)
5901746 - ISX800 Series w/ 52" Mower Deck (ISX800KAV2452)
5901777 - ISX800 Series w/ 61" Mower Deck (ISX800BE2761)
5901778 - ISX800 Series w/ 61" Mower Deck (ISX800BV2661SS)
5901790 - ISX800 Series w/ 52" Mower Deck (ISX800B2752SS)
5901791 - ISX800 Series w/ 61" Mower Deck (ISX800B2761SS)
5901818 - ISX800 CAL Series w/ 52" Mower Deck (ISX800KAV2452 CAL)
5901819 - ISX800 CAL Series w/ 61" Mower Deck (ISX800B2761SS CAL)
5901820 - ISX800 CAL Series w/ 61" Mower Deck (ISX800KAVE2661 CAL)
5901828 - ISX800 CE Series w/ 52" Rear Discharge Mower Deck (ISX800B2752RDCE)
5901834 - ISX800 CAL Series w/ 61" Mower Deck (ISX800BV2661SS CAL)
5901835 - ISX800 AUS Series w/ 52" Mower Deck (ISX800B2752 AUS)

*Part of Hydro-Gear fan/pulley kit 72656.