OK, so looking at it, it seems that the major thingsa holding it on, is the big yellow clamps on the axle tubes. Also its hard to see, but it may have brackets on the where the axle tubes bolt to the trans. I would not worry about that PTO housing behind the tranny for now, looks like the shaft will slip right out of there.
You have a full on shot of it, and the tractor??
I assume it will be REAL heavy, so you will want to get as much off of the main trancher frame before you go unbolting it.