per the parts list.. #1201342 was the part number for the jack up to B9473325... Which was a Shelley jack. The parts list shows 5220473 after that. My experience has been that the later jack (Metalfacture) was used exclusively in the MK2.. Of course, I could be wrong.... I will not claim to be omniscient!!! In any event, the later jack is at least an inch longer and is painted dk. grey, instead of black