Here is a 42 in Hydraulic Tiller that is set up for a GX345 but will work on 345, 355 as set up.  If you change the mounting hardware this would work on X500 garden tractors with Hydraulic deck lift.  Also would work on 425, 445, 455, x700 series tractor with three point mounting hardware.

I do not use this nearly enough to keep it around.  New one cost about $2500 from Deere.  This one is in great shape and works well.  Very powerful and heavy built.