Why would you need a skidplate? Well, the Achilles heel of Kubota's BX range is the plastic cooling fan for the Hydro system. It's a weak $10 part that takes 5 hours to replace. The blades can be broken when driving over branches and other large items littering the ground. A rear skidplate will protect it.
Bro-Tek Skidplate
Skidplates are manufactured by Bro-Tek - front and rear. To prevent the rear skidplate interfering with the mounting of a Mid-Mount mower, there is an opening to permit the PTO shaft to pass through if an MMM is installed. I believe however the front skidplate will not work with the mower - can anyone confirm?
If you own a BX25 or BX__60, your front skidplate will be a different shape. (Earlier skidplates do not fit the 2009 models without some extra cutting). Make sure you specify which tractor you have when ordering from BroTek.
Here's a good shot of the rear plate. Where you see the Bro-Tek log is the removable plate for mower PTO shaft. (It's not necessary to flip the tractor for installation but it helps!)
Skidplate and Mid-Mount Mower
Attaching a MidMount Mower with the skidplate in place can be tricky. Here are some thoughts on that problem. [TBN] BX skid plate and MMM