Since the first time I did this, many years ago, I've found it best to replae the seal for the inboard side of the joint any time I replace an axle. it adds about $10 and a couple minutes to the job but I think it's worth it. Also, lightly grease the edge of the joint going into the transmission (that is going to be the first part of the axle to go into the seal. Manual, I use oil, auto I use transmission fluid. This keeps it from binding on the outside of the seal and tearing or distorting it.