Diesel Boy -
I am almost 100% sure that Kubota does not make a skid plate for the Grand L's, and I have a feeling that holds true for every Kubota ever made.
A skid plate is high on my list of things to do on my L - I'm going to make it nice and thick (5/8" maybe) for protection and ballast. A backhoe subframe allows for one flat piece of steel plate to clear everything under the tractor, or you could accomplish the same thing by locating the top of the plate about 1.5" below the bottom of the loader frame rails.
Of course you'll lose about 2" of ground clearance, but the Grand L's have a little bit to spare. And you'd have some nice ballast right where you want, and a bullet-proof underside.
Got a friend with a nice big plasma cutter? /forums/images/graemlins/smile.gif
Take care, John