what SK Farmer says plus..
the cleaning fan cage is a Big one. I just found out this morning that my 9540 had it done.. it is a 45 hr job to change it out.. thrush washers in tranny, the coupler between Hydro motor and tranny needs to have an internal Lube line installed. brakes updated, check the universal joint on the bubble up auger(they came with a grease jerk but no mention of it in the owner's manual so most weren't)
also I believe there was an update to the clutches (motor to gear box back to rotor) mine had something done.