No need to split the tractor on a 129 to change hydro unit, unbolt trans linkage, knock the roll pins out of the brake levers,put a pan under it remove filter and pick-up tube let it drain a while and pull the hydro out through the tunnel !easy peasy ! but first I'd undo the drive shaft coupling and turn the hydro by hand to verify that's where it's coming from . You can pull the hydro pump that way in about a half hour ,you'll lose some fluid but if the drain pan is clean run it through a paint strainer and reuse it if it's new !
