As Gary said I doubt you would find a MMM. You could cange a RFM to work by changing the blades of the belt routing. From memory there was one available, it ran off a electric PTO clutch from the front engine crankshaft. You might be able to find one from an old Yanmar tractor that you could make fit, if you could accomodate for the reverse direction.
On the
B6000 the engine rotates the wrong way to standard, you can always tell a
B6000 by the fact the exhaust is on the right hand side, a normal Kubota will exhaust on the left. This in turn makes the PTO and transmission non standard.
On the up side you will find that a snow plough will be easier to find, you could always easily adapt one from another tractor if need be. (I believe the
B6100 and B6001 use the same plough, you might try looking for one of them.)
I think a common feature with
B6000 owners will be a need to adapt other implements to fit, with the reverse PTO it is very limiting what you can use. It is possible to buy a PTO converter but expect to pay a premium.
Sorry to be so negative, implements for the
B6000 are not common. The
B6000 is a nice tractor, despite all its issues I regret selling mine.
If you are interested I can send you some mower deck manuals for a
B6100 that might shed light on what you are looking for, though it will be a version that rotates the wrong way for your tractor. I also have a full set of
B6000 manuals if you want.
Thanks