Stay away from Power shuttle if doing loader work. Problem is that as back end is basically the same as old MF135, there isn't enough oil capacity to cope with loader,and p/shuttle clutches, which results in pressure drop so clutch can slip, plus reduced oil flow over clutch plates thus reduced cooling. If no loader work then p.shuttle will work not too badly. It was for this reason that MF stopped p/shuttle option way back in 2000.
12x12 manual shuttle fairly bomb proof, reliable and parts ready available should it need any tinkering with, however you cannot retrofit creeper gears to this box. Was only ever available as factory fit option..(not enough space here to explain why). Worth considering if u have possible requirement for such low speeds. Great tractor otherwise