just undo the four M12 bolts around the PTO shaft on the back, and pull that bush out. It keeps the bearing in place and once its out, you can push the shaft seal out to that end.
If necessary, pull the PTO shaft a little to get some room behind the bush, by attaching a PTO shaft coupler to have something to pull or pry on. If you pull it too far, you have to realign the last 60cm of shaft into the front piece by dropping the pump plate underneath the tractor to get in with your hand to guide it into place.